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Masatoshi Mita - One of the best experts on this subject based on the ideXlab platform.
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Effect of Relaxin-Like Gonad-Stimulating Substance on Gamete Shedding and 1-Methyladenine Production in Starfish Ovaries
Sexual Reproduction in Animals and Plants, 2014Co-Authors: Masatoshi Mita, Yuki Takeshige, Masaru NakamuraAbstract:As in lower vertebrates, starfish oocyte maturation and ovulation are induced by a hormonal substance. Gonad-stimulating substance (GSS) is the first mediator in inducing these maturation and ovulation. GSS secreted from the nervous system acts on the ovary to produce 1-Methyladenine (1-MeAde) as a maturation-inducing hormone. 1-MeAde induces germinal vesicle breakdown (GVBD) and follicular envelope breakdown (FEBD), releasing the oocyte from the ovaries, that is, spawning. Recently, GSS was purified from the radial nerves of the starfish Asterina pectinifera and its chemical structure was determined to be a relaxin-like peptide. To further elucidate the physiological roles of GSS on oocyte maturation and ovulation, this study examined the effect of synthetic GSS on 1-MeAde production in intact ovaries, folliculated oocytes, isolated follicle cells, and spawned ovaries containing follicle cells of the starfish (sea star) A. pectinifera. Spawning was induced by synthetic GSS as a dose-dependent manner. However, a high concentration of GSS failed to induce spawning. 1-MeAde production in an ovarian fragment also declined at a high concentration of GSS. Similar dual effects of GSS were observed in folliculated oocytes. In contrast, 1-MeAde production in isolated follicle cells and spawned ovaries did not decrease at a high concentration of GSS. Interestingly, egg jelly inhibited GSS-induced 1-MeAde production in follicle cells. These results may suggest that egg jelly disturbs GSS action on 1-MeAde production and spawning in ovaries.
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Incapacity of 1-Methyladenine Production to Relaxin-Like Gonad-Stimulating Substance in Ca2+-Free Seawater-Treated Starfish Ovarian Follicle Cells
Sexual Reproduction in Animals and Plants, 2014Co-Authors: Miho Watanabe, Kazutoshi Yamamoto, Masatoshi MitaAbstract:Previous studies have shown that brief treatment of follicle cells from ovaries of the starfish Asterina pectinifera with Ca2+-free seawater (CaFSW) deprived the follicle cells of their capacity to respond to gonad-stimulating substance (GSS). To elucidate the failure of GSS, this study examined the hormonal action of GSS on CaFSW-treated follicle cells of A. pectinifera, particularly the mode of signal transduction. GSS failed to stimulate the production of 1-Methyladenine (1-MeAde) and cyclic AMP (cAMP) in CaFSW-treated follicle cells and the incapacity was irreversible. According to competitive experiments using radioiodinated and radioinert GSS, highly specific binding was observed in follicle cells, although their affinities and binding sites in CaFSW-treated follicle cells were absolutely inferior to those in intact cells. Furthermore, GSS did not stimulate adenylyl cyclase in membrane preparations of CaFSW-treated follicle cells. Both Gsα and Giα were detected immunologically in membranes of CaFSW-treated follicle cells as well as those of nontreated cells. These results suggest that signal transduction for GSS in CaFSW-treated follicle cells does not flow readily from GSS receptors to G proteins.
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Contribution of de novo synthesis of Gαs-proteins to 1-Methyladenine production in starfish ovarian follicle cells stimulated by relaxin-like gonad-stimulating substance
Biochemical and Biophysical Research Communications, 2013Co-Authors: Masatoshi Mita, Shogo Haraguchi, Haruka Uzawa, Kazuyoshi TsutsuiAbstract:In starfish, the peptide hormone gonad-stimulating substance (GSS) secreted from nervous tissue stimulates oocyte maturation to induce 1-Methyladenine (1-MeAde) production by ovarian follicle cells. The hormonal action of GSS on follicle cells involves its receptor, G-proteins and adenylyl cyclase. However, GSS failed to induce 1-MeAde and cAMP production in follicle cells of ovaries during oogenesis. At the maturation stage, follicle cells acquired the potential to respond to GSS by producing 1-MeAde and cAMP. Adenylyl cyclase activity in follicle cells of fully grown stage ovaries was also stimulated by GSS in the presence of GTP. These activations depended on the size of oocytes in ovaries. The α subunit of Gs-proteins was not detected immunologically in follicle cells of oogenesis stage ovaries, although Gαi and Gαq were detectable. Using specific primers for Gαs and Gαi, expression levels of Gαs in follicle cells were found to increase significantly as the size of oocytes in ovaries increased, whereas the mRNA levels of Gαi were almost constant regardless of oocyte size. These findings strongly suggest the potential of follicle cells to respond to GSS by producing 1-MeAde and cAMP is brought by de novo synthesis of Gαs-proteins.
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Interaction of N1-substituted adenines with 1-Methyladenine receptors of starfish oocytes in induction of maturation.
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 2001Co-Authors: Masatoshi Mita, Michiyasu Yoshikuni, Yoshitaka Nagahama, Minako Maekawa, Miho Saito, Mineo SaneyoshiAbstract:Abstract Starfish oocytes are arrested naturally in the late G 2 phase of the first meiotic division. In response to the natural maturation-inducing hormone, 1-Methyladenine (1-MA), oocytes undergo reinitiation of meiosis with germinal vesicle breakdown. We tested 10 newly synthesized N1-substituted adenines that are 1-MA analogues to analyze the interaction between 1-MA and its stereo-specific receptors on the oocyte plasma membranes of the starfish Asterina pectinifera . Among these analogues, 1-(β-naphthylmethyl)adenine, 1-aminoadenine and 1-( p -nitrobenzyl)adenine played agonistic roles in the induction of oocyte maturation. 1-( o -Nitrobenzyl)adenine, 1-( m -nitrobenzyl)adenine, 1-phenethyladenine and 1-( p -nitrophenethyl)adenine had antagonist effects on 1-MA-induced oocyte maturation. These agonists and antagonists behaved competitively in the binding of [ 3 H]1-MA to receptors in oocyte cortices. In contrast, 1-(α-naphthylmethyl)adenine, 1-(2,4-dinitrobenzyl)adenine and 1-( p -methoxybenzyl)adenine had no effects on oocyte maturation. Our results suggest that regional-specific sterical structures at the N1-site of adenine are important in the interaction between 1-MA and its receptors in oocytes. In addition, a negative charge at the N1-site of adenine is required for binding with the receptors.
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1-Methyladenine production from ATP by starfish ovarian follicle cells.
Biochimica et Biophysica Acta (BBA) - General Subjects, 1999Co-Authors: Masatoshi Mita, Michiyasu Yoshikuni, Yoshitaka NagahamaAbstract:1-Methyladenine (1-MeAde), the oocyte maturation-inducing substance in starfish, is produced by ovarian follicle cells upon stimulation with a gonad-stimulating substance (GSS) released from the radial nerves. We have shown previously that GSS causes a reduction in the intracellular levels of ATP coincident with 1-MeAde production. The present study examined whether the adenine molecule of 1-MeAde is directly derived from ATP. When isolated follicle cells from the starfish Asterina pectinifera were preloaded with [U-14C]adenine or [U-14C]adenosine, there was an increase in the intracellular levels of radiolabeled adenine nucleotides, particularly ATP. Following further incubation with GSS, the intracellular levels of radiolabeled ATP decreased, concomitant with a marked increase in the levels of [14C]1-MeAde in the medium. The amount of ATP consumed under the influence of GSS was similar to the amount of 1-MeAde produced. However, there was no change in the levels of ADP and AMP regardless of the presence or absence of GSS. These findings strongly suggest that 1-MeAde is synthesized from ATP as a substrate in follicle cells under the influence of GSS. Furthermore, using [methyl-3H]methionine, the methyl group of 1-MeAde was found to be derived from methionine. Thus GSS appears to stimulate the synthesis of 1-MeAde from ATP via the methylation process in starfish ovarian follicle cells.
Motonori Hoshi - One of the best experts on this subject based on the ideXlab platform.
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G-Protein βγ Subunit-Dependent Phosphorylation of 62-kDa Protein in the Early Signaling Pathway of Starfish Oocyte Maturation Induced by 1-Methyladenine
Developmental Biology, 1999Co-Authors: Tsuyoshi Nakano, Motonori Hoshi, Toshiaki Katada, Kenji Kontani, Hiroshi Kurosu, Kazuyoshi ChibaAbstract:Abstract In starfish oocytes, maturation is induced by a hormone, 1-Methyladenine (1-MA), that binds to the receptors exposed to the outer surface of the plasma membrane. The signal of 1-MA stimulates the heterotrimeric G protein, resulting in dissociation of the βγ subunit of G protein (Gβγ) from a pertussis toxin-sensitive G i -type α subunit. To investigate the targets for Gβγ, we analyzed 1-MA- or Gβγ-dependent phosphorylation using in vivo and in vitro systems. A 62-kDa protein was phosphorylated immediately after 1-MA treatment in intact oocytes. In the cell-free preparations, the 62-kDa protein was also phosphorylated on serine residue(s) immediately after addition of 1-MA or Gβγ. The Gβγ-dependent phosphorylation of the 62-kDa protein was inhibited by wortmannin or LY294002, which are mechanistically different inhibitors of phosphatidylinositol 3-kinase (PI3K). LY294002 also inhibited Gβγ- as well as 1-MA-induced maturation of oocytes. Taken together, these results indicate that the 62-kDa protein functions downstream of Gβγ and PI3K in the early signaling pathway of 1-MA-induced starfish oocyte maturation. The phosphorylation of the 62-kDa protein may be required for the activation of maturation-promoting factor.
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G protein function in starfish oocyte maturation
Invertebrate Reproduction & Development, 1996Co-Authors: Kazuyoshi Chiba, Motonori HoshiAbstract:Summary Oocyte maturation of starfish is induced by 1-Methyladenine. 1-Methyladenine binds to the receptor exposed to the outer surface of the plasma membrane and me signal of 1-Methyladenine is transduced to the heterotrimeric G protein, resulting in dissociation of Gβγ from Gα. The dissociated Gβγ is likely to interact with the cytoplasmic effector, which is responsible for formation of MPF and for induction of GVBD. The G protein βγ subunit distributes segmentally on the continuous cytokeratin filaments as well as on the plasma membrane.
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G-protein-mediated signal transduction for meiosis reinitiation in starfish oocyte
Progress in Cell Cycle Research, 1995Co-Authors: Kazuyoshi Chiba, Motonori HoshiAbstract:Starfish oocyte maturation is induced by 1-Methyladenine. There were apparently two forms of 1-Methyladenine receptor affected by GTPγS. Pertussis toxin ADP-ribosylated the 39-kDa α subunit of a G protein and inhibited maturation. Also, the G protein was ADP- ribosylated by cholera toxin only when 1-Methyladenine was added. The purified G protein had an heterotrimeric structure consisting of 39 kDa a, 37 kDa β, and 8 kDa γ subunits. The deduced amino acid sequence of the cDNA of starfish Gα was 89% identical to mammalian Gi-1 α. The purified starfish βγsubunits induced maturation when they were microinjected into oocytes.
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the primary structure of the α subunit of a starfish guanosine nucleotide binding regulatory protein involved in 1 Methyladenine induced oocyte maturation
FEBS Journal, 1992Co-Authors: Kazuyoshi Chiba, Midori Matsumoto, Hirohiko Tadenuma, Katsunobu Takahashi, Toshiaki Katada, Motonori HoshiAbstract:Starfish-oocyte maturation induced by 1-Methyladenine (MeAde) was inhibited by microinjection of pertussis toxin (PTX). The inhibition appeared to result from PTX-catalyzed ADP-ribosylation of a 39-kDa guanosine-nucleotide-binding regulatory protein (G protein) in the oocyte. These results strongly support the hypothesis that the MeAde-induced signals operate via a membrane receptor and are carried by the PTX-sensitive G protein. When PTX-injected oocytes were treated with dithiothreitol, 85% of them reinitiated meiosis, suggesting that dithiothreitol did not act on the MeAde receptor. We constructed a cDNA library from the immature ovary of starfish, Asterina pectinifera, and screened it with the cDNA of the α subunit of an inhibitory rat G protein (Gi-2), A positive cDNA clone contained an open reading frame of 1062 bases which had 74% identity with the rat Gi-2 cDNA. The deduced amino acid sequence was 85% and 89% identical to rat Gi-2 and rat Gi-1, respectively. The α subunit of the G protein purified from cortices of starfish oocytes was digested by trypsin and the resulting four peptides were microsequenced. Comparison of these amino acid sequences with the predicted one indicated that the isolated cDNA clone encoded the α subunit of the PTX-sensitive G protein in oocytes. The C-terminal sequence, KNNLKDCGLF, was identical to that of Gi, suggesting that the cysteine residue is the site of ADP-ribosylation.
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Pertussis toxin-sensitive G protein participating in starfish oocyte maturation induced by 1-Methyladenine
Invertebrate Reproduction & Development, 1992Co-Authors: Motonori Hoshi, Kazuyoshi Chiba, Midori Matsumoto, Hirohiko Tadenuma, Katsunobu Takahashi, Toshiaki KatadaAbstract:Summary 1-Methyladenine (1-MA) secreted from the follicle cells is the biological signal for meiosis reinitiation of starfish oocytes. The signal of-1-MA is transduced into cytoplasmic formation of maturation-promoting factor (MPF) that eventually induces a germinal vesicle breakdown (GVBD). Microinjection of pertussis toxin (PTX) inhibited 1-MA-induced GVBD in Asterina pectinifera and Asterina (Patina) miniata. PTX-inhibition of GVBD was rescued by the injection of MPF into PTX-preinjected oocytes. Most of the PTX- and MPF-double injected eggs were fertilized and underwent cleavage, suggesting the presence of a GTP-binding protein (G protein) specific for 1-MA signal transduction. Indeed, plasma membrane preparations of A. pectinifera oocytes contained a G protein consisting of 39-kDa α, 37-kDa β, and 8-kDa γ subunits. The α subunit contained a site for ADP-ribosylation catalyzed by PTX. It was also recognized by antibodies specific for a common GTP-binding site of mammalian α subunits or a carboxy-termi...
Kazuyoshi Chiba - One of the best experts on this subject based on the ideXlab platform.
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G-Protein βγ Subunit-Dependent Phosphorylation of 62-kDa Protein in the Early Signaling Pathway of Starfish Oocyte Maturation Induced by 1-Methyladenine
Developmental Biology, 1999Co-Authors: Tsuyoshi Nakano, Motonori Hoshi, Toshiaki Katada, Kenji Kontani, Hiroshi Kurosu, Kazuyoshi ChibaAbstract:Abstract In starfish oocytes, maturation is induced by a hormone, 1-Methyladenine (1-MA), that binds to the receptors exposed to the outer surface of the plasma membrane. The signal of 1-MA stimulates the heterotrimeric G protein, resulting in dissociation of the βγ subunit of G protein (Gβγ) from a pertussis toxin-sensitive G i -type α subunit. To investigate the targets for Gβγ, we analyzed 1-MA- or Gβγ-dependent phosphorylation using in vivo and in vitro systems. A 62-kDa protein was phosphorylated immediately after 1-MA treatment in intact oocytes. In the cell-free preparations, the 62-kDa protein was also phosphorylated on serine residue(s) immediately after addition of 1-MA or Gβγ. The Gβγ-dependent phosphorylation of the 62-kDa protein was inhibited by wortmannin or LY294002, which are mechanistically different inhibitors of phosphatidylinositol 3-kinase (PI3K). LY294002 also inhibited Gβγ- as well as 1-MA-induced maturation of oocytes. Taken together, these results indicate that the 62-kDa protein functions downstream of Gβγ and PI3K in the early signaling pathway of 1-MA-induced starfish oocyte maturation. The phosphorylation of the 62-kDa protein may be required for the activation of maturation-promoting factor.
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G protein function in starfish oocyte maturation
Invertebrate Reproduction & Development, 1996Co-Authors: Kazuyoshi Chiba, Motonori HoshiAbstract:Summary Oocyte maturation of starfish is induced by 1-Methyladenine. 1-Methyladenine binds to the receptor exposed to the outer surface of the plasma membrane and me signal of 1-Methyladenine is transduced to the heterotrimeric G protein, resulting in dissociation of Gβγ from Gα. The dissociated Gβγ is likely to interact with the cytoplasmic effector, which is responsible for formation of MPF and for induction of GVBD. The G protein βγ subunit distributes segmentally on the continuous cytokeratin filaments as well as on the plasma membrane.
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G-protein-mediated signal transduction for meiosis reinitiation in starfish oocyte
Progress in Cell Cycle Research, 1995Co-Authors: Kazuyoshi Chiba, Motonori HoshiAbstract:Starfish oocyte maturation is induced by 1-Methyladenine. There were apparently two forms of 1-Methyladenine receptor affected by GTPγS. Pertussis toxin ADP-ribosylated the 39-kDa α subunit of a G protein and inhibited maturation. Also, the G protein was ADP- ribosylated by cholera toxin only when 1-Methyladenine was added. The purified G protein had an heterotrimeric structure consisting of 39 kDa a, 37 kDa β, and 8 kDa γ subunits. The deduced amino acid sequence of the cDNA of starfish Gα was 89% identical to mammalian Gi-1 α. The purified starfish βγsubunits induced maturation when they were microinjected into oocytes.
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the primary structure of the α subunit of a starfish guanosine nucleotide binding regulatory protein involved in 1 Methyladenine induced oocyte maturation
FEBS Journal, 1992Co-Authors: Kazuyoshi Chiba, Midori Matsumoto, Hirohiko Tadenuma, Katsunobu Takahashi, Toshiaki Katada, Motonori HoshiAbstract:Starfish-oocyte maturation induced by 1-Methyladenine (MeAde) was inhibited by microinjection of pertussis toxin (PTX). The inhibition appeared to result from PTX-catalyzed ADP-ribosylation of a 39-kDa guanosine-nucleotide-binding regulatory protein (G protein) in the oocyte. These results strongly support the hypothesis that the MeAde-induced signals operate via a membrane receptor and are carried by the PTX-sensitive G protein. When PTX-injected oocytes were treated with dithiothreitol, 85% of them reinitiated meiosis, suggesting that dithiothreitol did not act on the MeAde receptor. We constructed a cDNA library from the immature ovary of starfish, Asterina pectinifera, and screened it with the cDNA of the α subunit of an inhibitory rat G protein (Gi-2), A positive cDNA clone contained an open reading frame of 1062 bases which had 74% identity with the rat Gi-2 cDNA. The deduced amino acid sequence was 85% and 89% identical to rat Gi-2 and rat Gi-1, respectively. The α subunit of the G protein purified from cortices of starfish oocytes was digested by trypsin and the resulting four peptides were microsequenced. Comparison of these amino acid sequences with the predicted one indicated that the isolated cDNA clone encoded the α subunit of the PTX-sensitive G protein in oocytes. The C-terminal sequence, KNNLKDCGLF, was identical to that of Gi, suggesting that the cysteine residue is the site of ADP-ribosylation.
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Pertussis toxin-sensitive G protein participating in starfish oocyte maturation induced by 1-Methyladenine
Invertebrate Reproduction & Development, 1992Co-Authors: Motonori Hoshi, Kazuyoshi Chiba, Midori Matsumoto, Hirohiko Tadenuma, Katsunobu Takahashi, Toshiaki KatadaAbstract:Summary 1-Methyladenine (1-MA) secreted from the follicle cells is the biological signal for meiosis reinitiation of starfish oocytes. The signal of-1-MA is transduced into cytoplasmic formation of maturation-promoting factor (MPF) that eventually induces a germinal vesicle breakdown (GVBD). Microinjection of pertussis toxin (PTX) inhibited 1-MA-induced GVBD in Asterina pectinifera and Asterina (Patina) miniata. PTX-inhibition of GVBD was rescued by the injection of MPF into PTX-preinjected oocytes. Most of the PTX- and MPF-double injected eggs were fertilized and underwent cleavage, suggesting the presence of a GTP-binding protein (G protein) specific for 1-MA signal transduction. Indeed, plasma membrane preparations of A. pectinifera oocytes contained a G protein consisting of 39-kDa α, 37-kDa β, and 8-kDa γ subunits. The α subunit contained a site for ADP-ribosylation catalyzed by PTX. It was also recognized by antibodies specific for a common GTP-binding site of mammalian α subunits or a carboxy-termi...
Toshiaki Katada - One of the best experts on this subject based on the ideXlab platform.
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G-Protein βγ Subunit-Dependent Phosphorylation of 62-kDa Protein in the Early Signaling Pathway of Starfish Oocyte Maturation Induced by 1-Methyladenine
Developmental Biology, 1999Co-Authors: Tsuyoshi Nakano, Motonori Hoshi, Toshiaki Katada, Kenji Kontani, Hiroshi Kurosu, Kazuyoshi ChibaAbstract:Abstract In starfish oocytes, maturation is induced by a hormone, 1-Methyladenine (1-MA), that binds to the receptors exposed to the outer surface of the plasma membrane. The signal of 1-MA stimulates the heterotrimeric G protein, resulting in dissociation of the βγ subunit of G protein (Gβγ) from a pertussis toxin-sensitive G i -type α subunit. To investigate the targets for Gβγ, we analyzed 1-MA- or Gβγ-dependent phosphorylation using in vivo and in vitro systems. A 62-kDa protein was phosphorylated immediately after 1-MA treatment in intact oocytes. In the cell-free preparations, the 62-kDa protein was also phosphorylated on serine residue(s) immediately after addition of 1-MA or Gβγ. The Gβγ-dependent phosphorylation of the 62-kDa protein was inhibited by wortmannin or LY294002, which are mechanistically different inhibitors of phosphatidylinositol 3-kinase (PI3K). LY294002 also inhibited Gβγ- as well as 1-MA-induced maturation of oocytes. Taken together, these results indicate that the 62-kDa protein functions downstream of Gβγ and PI3K in the early signaling pathway of 1-MA-induced starfish oocyte maturation. The phosphorylation of the 62-kDa protein may be required for the activation of maturation-promoting factor.
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the primary structure of the α subunit of a starfish guanosine nucleotide binding regulatory protein involved in 1 Methyladenine induced oocyte maturation
FEBS Journal, 1992Co-Authors: Kazuyoshi Chiba, Midori Matsumoto, Hirohiko Tadenuma, Katsunobu Takahashi, Toshiaki Katada, Motonori HoshiAbstract:Starfish-oocyte maturation induced by 1-Methyladenine (MeAde) was inhibited by microinjection of pertussis toxin (PTX). The inhibition appeared to result from PTX-catalyzed ADP-ribosylation of a 39-kDa guanosine-nucleotide-binding regulatory protein (G protein) in the oocyte. These results strongly support the hypothesis that the MeAde-induced signals operate via a membrane receptor and are carried by the PTX-sensitive G protein. When PTX-injected oocytes were treated with dithiothreitol, 85% of them reinitiated meiosis, suggesting that dithiothreitol did not act on the MeAde receptor. We constructed a cDNA library from the immature ovary of starfish, Asterina pectinifera, and screened it with the cDNA of the α subunit of an inhibitory rat G protein (Gi-2), A positive cDNA clone contained an open reading frame of 1062 bases which had 74% identity with the rat Gi-2 cDNA. The deduced amino acid sequence was 85% and 89% identical to rat Gi-2 and rat Gi-1, respectively. The α subunit of the G protein purified from cortices of starfish oocytes was digested by trypsin and the resulting four peptides were microsequenced. Comparison of these amino acid sequences with the predicted one indicated that the isolated cDNA clone encoded the α subunit of the PTX-sensitive G protein in oocytes. The C-terminal sequence, KNNLKDCGLF, was identical to that of Gi, suggesting that the cysteine residue is the site of ADP-ribosylation.
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Pertussis toxin-sensitive G protein participating in starfish oocyte maturation induced by 1-Methyladenine
Invertebrate Reproduction & Development, 1992Co-Authors: Motonori Hoshi, Kazuyoshi Chiba, Midori Matsumoto, Hirohiko Tadenuma, Katsunobu Takahashi, Toshiaki KatadaAbstract:Summary 1-Methyladenine (1-MA) secreted from the follicle cells is the biological signal for meiosis reinitiation of starfish oocytes. The signal of-1-MA is transduced into cytoplasmic formation of maturation-promoting factor (MPF) that eventually induces a germinal vesicle breakdown (GVBD). Microinjection of pertussis toxin (PTX) inhibited 1-MA-induced GVBD in Asterina pectinifera and Asterina (Patina) miniata. PTX-inhibition of GVBD was rescued by the injection of MPF into PTX-preinjected oocytes. Most of the PTX- and MPF-double injected eggs were fertilized and underwent cleavage, suggesting the presence of a GTP-binding protein (G protein) specific for 1-MA signal transduction. Indeed, plasma membrane preparations of A. pectinifera oocytes contained a G protein consisting of 39-kDa α, 37-kDa β, and 8-kDa γ subunits. The α subunit contained a site for ADP-ribosylation catalyzed by PTX. It was also recognized by antibodies specific for a common GTP-binding site of mammalian α subunits or a carboxy-termi...
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Properties of 1-Methyladenine receptors in starfish oocyte membranes: involvement of pertussis toxin-sensitive GTP-binding protein in the receptor-mediated signal transduction.
Biochemical and Biophysical Research Communications, 1992Co-Authors: Hirohiko Tadenuma, Kazuyoshi Chiba, Motonori Hoshi, Katsunobu Takahashi, Toshiaki KatadaAbstract:Summary In response to a meiosis-inducing hormone, 1-Methyladenine (1-MA), starfish oocytes undergo reinitiation of meiosis with germinal vesicle breakdown. The 1-MA-initiated signal is, however, inhibited by prior microinjection of pertussis toxin into the oocytes, suggesting that a guanine nucleotide-binding protein (G protein) serving as the substrate of pertussis toxin is involved in the 1-MA receptor-mediated signal. We thus investigated properties of 1-MA receptors by means of binding of the radiolabeled ligand to the oocyte membranes. There were apparently two forms of 1-MA receptors with high and low affinities in the membranes. The high-affinity form was converted into the low-affinity one in the presence of a non-hydrolyzable analogue of GTP. A 39-kDa protein, which had been identified as the α-subunit of the major substrate G protein for pertussis toxin, was also ADPribosylated by cholera toxin only when 1-MA was added to the membranes. The ADPribosylated 39-kDa α-subunit could be immunoprecipitated with antibodies raised against the carboxy-terminal site of mammalian inhibitory G-α. These results indicate that 1-MA receptors are functionally coupled with the 39-kDa pertussis toxin-substrate G protein in starfish oocyte membranes.
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The primary structure of the α subunit of a starfish guanosine‐nucleotide‐binding regulatory protein involved in 1‐Methyladenine‐induced oocyte maturation
European Journal of Biochemistry, 1992Co-Authors: Kazuyoshi Chiba, Midori Matsumoto, Hirohiko Tadenuma, Katsunobu Takahashi, Toshiaki Katada, Motonori HoshiAbstract:Starfish-oocyte maturation induced by 1-Methyladenine (MeAde) was inhibited by microinjection of pertussis toxin (PTX). The inhibition appeared to result from PTX-catalyzed ADP-ribosylation of a 39-kDa guanosine-nucleotide-binding regulatory protein (G protein) in the oocyte. These results strongly support the hypothesis that the MeAde-induced signals operate via a membrane receptor and are carried by the PTX-sensitive G protein. When PTX-injected oocytes were treated with dithiothreitol, 85% of them reinitiated meiosis, suggesting that dithiothreitol did not act on the MeAde receptor. We constructed a cDNA library from the immature ovary of starfish, Asterina pectinifera, and screened it with the cDNA of the α subunit of an inhibitory rat G protein (Gi-2), A positive cDNA clone contained an open reading frame of 1062 bases which had 74% identity with the rat Gi-2 cDNA. The deduced amino acid sequence was 85% and 89% identical to rat Gi-2 and rat Gi-1, respectively. The α subunit of the G protein purified from cortices of starfish oocytes was digested by trypsin and the resulting four peptides were microsequenced. Comparison of these amino acid sequences with the predicted one indicated that the isolated cDNA clone encoded the α subunit of the PTX-sensitive G protein in oocytes. The C-terminal sequence, KNNLKDCGLF, was identical to that of Gi, suggesting that the cysteine residue is the site of ADP-ribosylation.
Hirohiko Tadenuma - One of the best experts on this subject based on the ideXlab platform.
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the primary structure of the α subunit of a starfish guanosine nucleotide binding regulatory protein involved in 1 Methyladenine induced oocyte maturation
FEBS Journal, 1992Co-Authors: Kazuyoshi Chiba, Midori Matsumoto, Hirohiko Tadenuma, Katsunobu Takahashi, Toshiaki Katada, Motonori HoshiAbstract:Starfish-oocyte maturation induced by 1-Methyladenine (MeAde) was inhibited by microinjection of pertussis toxin (PTX). The inhibition appeared to result from PTX-catalyzed ADP-ribosylation of a 39-kDa guanosine-nucleotide-binding regulatory protein (G protein) in the oocyte. These results strongly support the hypothesis that the MeAde-induced signals operate via a membrane receptor and are carried by the PTX-sensitive G protein. When PTX-injected oocytes were treated with dithiothreitol, 85% of them reinitiated meiosis, suggesting that dithiothreitol did not act on the MeAde receptor. We constructed a cDNA library from the immature ovary of starfish, Asterina pectinifera, and screened it with the cDNA of the α subunit of an inhibitory rat G protein (Gi-2), A positive cDNA clone contained an open reading frame of 1062 bases which had 74% identity with the rat Gi-2 cDNA. The deduced amino acid sequence was 85% and 89% identical to rat Gi-2 and rat Gi-1, respectively. The α subunit of the G protein purified from cortices of starfish oocytes was digested by trypsin and the resulting four peptides were microsequenced. Comparison of these amino acid sequences with the predicted one indicated that the isolated cDNA clone encoded the α subunit of the PTX-sensitive G protein in oocytes. The C-terminal sequence, KNNLKDCGLF, was identical to that of Gi, suggesting that the cysteine residue is the site of ADP-ribosylation.
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Pertussis toxin-sensitive G protein participating in starfish oocyte maturation induced by 1-Methyladenine
Invertebrate Reproduction & Development, 1992Co-Authors: Motonori Hoshi, Kazuyoshi Chiba, Midori Matsumoto, Hirohiko Tadenuma, Katsunobu Takahashi, Toshiaki KatadaAbstract:Summary 1-Methyladenine (1-MA) secreted from the follicle cells is the biological signal for meiosis reinitiation of starfish oocytes. The signal of-1-MA is transduced into cytoplasmic formation of maturation-promoting factor (MPF) that eventually induces a germinal vesicle breakdown (GVBD). Microinjection of pertussis toxin (PTX) inhibited 1-MA-induced GVBD in Asterina pectinifera and Asterina (Patina) miniata. PTX-inhibition of GVBD was rescued by the injection of MPF into PTX-preinjected oocytes. Most of the PTX- and MPF-double injected eggs were fertilized and underwent cleavage, suggesting the presence of a GTP-binding protein (G protein) specific for 1-MA signal transduction. Indeed, plasma membrane preparations of A. pectinifera oocytes contained a G protein consisting of 39-kDa α, 37-kDa β, and 8-kDa γ subunits. The α subunit contained a site for ADP-ribosylation catalyzed by PTX. It was also recognized by antibodies specific for a common GTP-binding site of mammalian α subunits or a carboxy-termi...
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Properties of 1-Methyladenine receptors in starfish oocyte membranes: involvement of pertussis toxin-sensitive GTP-binding protein in the receptor-mediated signal transduction.
Biochemical and Biophysical Research Communications, 1992Co-Authors: Hirohiko Tadenuma, Kazuyoshi Chiba, Motonori Hoshi, Katsunobu Takahashi, Toshiaki KatadaAbstract:Summary In response to a meiosis-inducing hormone, 1-Methyladenine (1-MA), starfish oocytes undergo reinitiation of meiosis with germinal vesicle breakdown. The 1-MA-initiated signal is, however, inhibited by prior microinjection of pertussis toxin into the oocytes, suggesting that a guanine nucleotide-binding protein (G protein) serving as the substrate of pertussis toxin is involved in the 1-MA receptor-mediated signal. We thus investigated properties of 1-MA receptors by means of binding of the radiolabeled ligand to the oocyte membranes. There were apparently two forms of 1-MA receptors with high and low affinities in the membranes. The high-affinity form was converted into the low-affinity one in the presence of a non-hydrolyzable analogue of GTP. A 39-kDa protein, which had been identified as the α-subunit of the major substrate G protein for pertussis toxin, was also ADPribosylated by cholera toxin only when 1-MA was added to the membranes. The ADPribosylated 39-kDa α-subunit could be immunoprecipitated with antibodies raised against the carboxy-terminal site of mammalian inhibitory G-α. These results indicate that 1-MA receptors are functionally coupled with the 39-kDa pertussis toxin-substrate G protein in starfish oocyte membranes.
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The primary structure of the α subunit of a starfish guanosine‐nucleotide‐binding regulatory protein involved in 1‐Methyladenine‐induced oocyte maturation
European Journal of Biochemistry, 1992Co-Authors: Kazuyoshi Chiba, Midori Matsumoto, Hirohiko Tadenuma, Katsunobu Takahashi, Toshiaki Katada, Motonori HoshiAbstract:Starfish-oocyte maturation induced by 1-Methyladenine (MeAde) was inhibited by microinjection of pertussis toxin (PTX). The inhibition appeared to result from PTX-catalyzed ADP-ribosylation of a 39-kDa guanosine-nucleotide-binding regulatory protein (G protein) in the oocyte. These results strongly support the hypothesis that the MeAde-induced signals operate via a membrane receptor and are carried by the PTX-sensitive G protein. When PTX-injected oocytes were treated with dithiothreitol, 85% of them reinitiated meiosis, suggesting that dithiothreitol did not act on the MeAde receptor. We constructed a cDNA library from the immature ovary of starfish, Asterina pectinifera, and screened it with the cDNA of the α subunit of an inhibitory rat G protein (Gi-2), A positive cDNA clone contained an open reading frame of 1062 bases which had 74% identity with the rat Gi-2 cDNA. The deduced amino acid sequence was 85% and 89% identical to rat Gi-2 and rat Gi-1, respectively. The α subunit of the G protein purified from cortices of starfish oocytes was digested by trypsin and the resulting four peptides were microsequenced. Comparison of these amino acid sequences with the predicted one indicated that the isolated cDNA clone encoded the α subunit of the PTX-sensitive G protein in oocytes. The C-terminal sequence, KNNLKDCGLF, was identical to that of Gi, suggesting that the cysteine residue is the site of ADP-ribosylation.
