The Experts below are selected from a list of 912 Experts worldwide ranked by ideXlab platform
Jacqueline Chauvet - One of the best experts on this subject based on the ideXlab platform.
-
bony fish Neurophysins identification of msel and vldv Neurophysins of the pollack pollachius virens
International Journal of Peptide and Protein Research, 2009Co-Authors: Jacqueline Chauvet, Marie-thérèse ChauvetAbstract:The two types of Neurophysins known in vertebrate species, namely MSEL-Neurophysin (vasopressin-like hormone-associated Neurophysin) and VLDV-Neurophysin (oxytocin-like hormone-associated Neurophysin) have been purified from the pollack (Pollachius virens) pituitary through a combination of molecular sieving and high-pressure liquid chromatography (HPLC). Homogeneity has been checked by gel electrophoresis and rerun in HPLC. The apparent molecular masses measured by SDS-electrophoresis are near 12 kDa, significantly higher than those found for their mammalian homologues (10 kDa). The two types of Neurophysins have been recognized through their N-terminal amino acid sequences. The primary structure of MSEL-Neurophysin has been partially determined using automated Edman degradation applied on native and reduced-alkylated protein, as well as peptides derived by trypsin or staphylococcal proteinase hydrolyses. Comparison of pollack MSEL-Neurophysin with ox, goose and frog counterparts reveals that particular positions in the polypeptide chain are subjected to substitutions and that the numbers of substitutions do not seem closely related to the paleontological times of divergence between the different vertebrate classes.
-
guinea pig msel Neurophysin sequence comparison of eight mammalian msel Neurophysins
International Journal of Peptide and Protein Research, 2009Co-Authors: Marie-thérèse Chauvet, Jacqueline ChauvetAbstract:The amino acid sequence of guinea pig MSEL-Neurophysin has been determined using tryptic peptides derived from the performic acid-oxidized protein and staphylococcal proteinase peptides obtained from the reduced-carboxamidomethylated neur-ophysin. Guinea pig MSEL-Neurophysin consists of a 93-residue polypeptide chain that shows 12 substitutions and 2 deletions when compared to bovine MSEL-Neurophysin. It displays the highest number of variations among known mammalian MSEL-Neurophysins. These variations are mainly found in the C-terminal region (residues 88–93). Moreover guinea pig MSEL-Neurophysin, like rat homologous protein, exhibits substitutions in positions 2, 5, 29 and 81 and lacks an arginine in the penultimate position. Comparison between eight mammalian MSEL-Neurophysins reveals a highly conserved region (residues 1 to 88) and a hypervariable region (residues 89 to 93/95). On the other hand the eight species examined are endowed with arginine vasopressin except pig, which has a lysine vasopressin. In the vasopressin-MSEL-Neurophysin precursor, the hormonal moiety and the MSEL region of Neurophysin (residues 1–9) are encoded by a common exon in ox, rat and man; it can be concluded that this exon is evolutionarily conservative in contrast to the one encoding the C-terminal region of MSEL-Neurophysin.
-
non mammalian big Neurophysins complete amino acid sequence of a two domain msel Neurophysin from goose
International Journal of Peptide and Protein Research, 2009Co-Authors: G Michel, Brigitte Lévy, Marie-thérèse Chauvet, Jacqueline ChauvetAbstract:Vasotocin-associated Neurophysin (MSEL-Neurophysin) has been purified from goose neurohypophysis through molecular sieving and high-pressure reverse-phase liquid chromatography (HPLC). The protein has a molecular mass (measured by SDS-polyacrylamide gel electrophoresis) of 17 kDa in contrast to 10 kDa found for the mammalian MSEL-Neurophysins. Complete amino acid sequence (131 residues) has been determined mainly through tryptic or staphylococcal proteinase peptides derived from carboxyamidomethylated Neurophysin, isolated by HPLC and microsequenced. N- and C-terminal sequences have been established by Edman degradation or action of carboxypeptidase Y, respectively, applied on the native protein. Goose MSEL-Neurophysin is homologous to the two-domain "big" MSEL-Neurophysin previously identified in the frog. It appears that in non-mammalian tetrapods, namely birds and amphibians, the proteolytic processing of the pro-vasotocin involves only one cleavage, releasing the hormone moiety and a "big" Neurophysin with two domains homologous to mammalian MSEL-Neurophysin and copeptin, respectively. Comparison of the avian protein with its mammalian and amphibian counterparts reveals that the first half of the polypeptide chain is evolutionarily much less variable than the second and that the goose protein resembles the frog protein much more than the mammalian one.
-
ontogeny of bovine neurohypophysial hormone precursors ii foetal copeptin the third domain of the vasopressin precursor
International Journal of Peptide and Protein Research, 2009Co-Authors: Brigitte Lévy, Marietheereese Chauvet, Jacqueline ChauvetAbstract:Vasopressin, MSEL-Neurophysin and a glycopeptide, here referred to as copeptin, are three fragments of a common protein precursor processed during axonal transport from hypothalamus to neurohypophysis. Neurohormones and Neurophysins purified from 7-9-month-old bovine foetuses have previously been shown to be identical with those found in the adult. Copeptin has now been isolated from 7-9-month and 3-month-old bovine foetuses and chemically characterized. It can be concluded from the nature of the three precursors that the same vasopressin gene is expressed in the adult and the 7-9-month-old foetus.
-
non mammalian big Neurophysins complete amino acid sequence of a two domain msel Neurophysin from goose
International Journal of Peptide and Protein Research, 2009Co-Authors: G Michel, Brigitte Lévy, Jacqueline Chauvet, Marie-thérèse Chauvet, Roger AcherAbstract:Vasotocin-associated Neurophysin (MSEL-Neurophysin) has been purified from goose neurohypophysis through molecular sieving and high-pressure reverse-phase liquid chromatography (HPLC). The protein has a molecular mass (measured by SDS-polyacrylamide gel electrophoresis) of 17 kDa in contrast to 10 kDa found for the mammalian MSEL-Neurophysins. Complete amino acid sequence (131 residues) has been determined mainly through tryptic or staphylococcal proteinase peptides derived from carboxyamidomethylated Neurophysin, isolated by HPLC and microsequenced. N- and C-terminal sequences have been established by Edman degradation or action of carboxypeptidase Y, respectively, applied on the native protein. Goose MSEL-Neurophysin is homologous to the two-domain "big" MSEL-Neurophysin previously identified in the frog. It appears that in non-mammalian tetrapods, namely birds and amphibians, the proteolytic processing of the pro-vasotocin involves only one cleavage, releasing the hormone moiety and a "big" Neurophysin with two domains homologous to mammalian MSEL-Neurophysin and copeptin, respectively. Comparison of the avian protein with its mammalian and amphibian counterparts reveals that the first half of the polypeptide chain is evolutionarily much less variable than the second and that the goose protein resembles the frog protein much more than the mammalian one.
J Joosse - One of the best experts on this subject based on the ideXlab platform.
-
evolution of the vasopressin oxytocin superfamily characterization of a cdna encoding a vasopressin related precursor preproconopressin from the mollusc lymnaea stagnalis
Proceedings of the National Academy of Sciences of the United States of America, 1992Co-Authors: R E Van Kesteren, August B Smit, R W Dirks, W P M Geraerts, J JoosseAbstract:Abstract Although the nonapeptide hormones vasopressin, oxytocin, and related peptides from vertebrates and some nonapeptides from invertebrates share similarities in amino acid sequence, their evolutionary relationships are not clear. To investigate this issue, we cloned a cDNA encoding a vasopressin-related peptide, Lys-conopressin, produced in the central nervous system of the gastropod mollusc Lymnaea stagnalis. The predicted preproconopressin has the overall architecture of vertebrate preprovasopressin, with a signal peptide, Lys-conopressin, that is flanked at the C terminus by an amidation signal and a pair of basic residues, followed by a Neurophysin domain. The Lymnaea Neurophysin and the vertebrate Neurophysins share high sequence identity, which includes the conservation of all 14 cysteine residues. In addition, the Lymnaea Neurophysin possesses unique structural characteristics. It contains a putative N-linked glycosylation site at a position in the vertebrate Neurophysins where a strictly conserved tyrosine residue, which plays an essential role in binding of the nonapeptide hormones, is found. The C-terminal copeptin homologous extension of the Lymnaea Neurophysin has low sequence identity with the vertebrate counterparts and is probably not cleaved from the prohormone, as are the mammalian copeptins. The conopressin gene is expressed in only a few neurons in both pedal ganglia of the central nervous system. The conopressin transcript is present in two sizes, due to alternative use of polyadenylylation signals. The data presented here demonstrate that the typical organization of the prohormones of the vasopressin/oxytocin superfamily must have been present in the common ancestors of vertebrates and invertebrates.
Marc Ansseau - One of the best experts on this subject based on the ideXlab platform.
-
avp and ot Neurophysins response to apomorphine and clonidine in major depression
Psychoneuroendocrinology, 2005Co-Authors: Gabrielle Scantamburlo, Sonia Fuchs, Michel Hansenne, Jean Reggers, Emmanuel Pinto, William Pitchot, Marc Ansseau, Jean-jacques LegrosAbstract:A number of studies have reported abnormalities of neurohypophyseal secretions in major depressive disorder. The purpose of the present study was to test the influence of apomorphine and clonidine injections on plasma vasopressin (AVP)-Neurophysins and oxytocin(OT)-Neurophysins levels, as direct index of posterior pituitary activation in major depression. Apomorphine and clonidine tests were carried out in 25 medication-free depressive patients and 25 age and gender-matched healthy controls. Blood for Neurophysins analysis was drawn by venipuncture at t0, t+20, t+40, t+60 and t+120. Baseline AVP-Neurophysins concentrations were significantly lower in depressives (0.12±0.14 ng/ml) than in healthy subjects (0.24±2.15 ng/ml) (p<0.04). The response to apomorphine test revealed a significant reduced response at 20 (p=0.01), 40 (p=0.007) and 60 (p=0.02) and 120 (p=0.02) min. Following clonidine test, post hoc tests also revealed a significant decrease at 0 (p=0.04), 20 (p=0.01), 40 (p=0.007) and 60 (p=0.02) and 120 (p=0.006) min. Concerning OT-Neurophysins, no significant differences were found between depressed and controls in response to clonidine or apomorphine injections. Following clonidine and apomorphine, major depressives exhibited a significantly lower peak GH response than controls. The study supports partially the hypothesis of a reduced vasopressinergic activity in depression. Moreover, we did not find any influence of acute apomorphine or clonidine injections on vasopressin-Neurophysin or oxytocin-Neurophysin in depressive patients.
-
apomorphine stimulation of vasopressin and oxytocin Neurophysins evidence for increased oxytocinergic and decreased vasopressinergic function in schizophrenics
Psychoneuroendocrinology, 1992Co-Authors: Jean-jacques Legros, C Gazzotti, T Carvelli, M Timsitberthier, Remy Frenckell, Paul Franchimont, Marc AnsseauAbstract:Abstract Apomorphine challenge tests (0.5 mg SC) were performed in 14 normal male volunteers and in 9 male schizophrenic inpatients, drug-free for at least 2 wk. In the normal volunteers, apomorphine induced an increase of serum growth hormone (GH) (maximum at 40 min), of vasopressin-Neurophysin (hN P I) (maximum at 20 min), and oxytocin-Neurophysin (hN P II) (maximum at 20 min). The release of Neurophysins was independent of digestive side effects. In the schizophrenics, the GH level and release pattern were similar to those in the controls. The basal level of hN P I was reduced (t 0 : 0.42±0.1 ng/ml in the schizophrenics and 0.66±0.05 ng/ml in the controls, p P II was increased (3.34 ± 0.04 ng / ml in the schizophrenics to 0.92±0.21 ng/ml in the controls, p =0.001). The response to apomorphine was blunted, with no significant release of hN P I or of hN P II. Although the hN P II data are consistent with an increased dopaminergic tone, the psychopathological meaning of the increased basal oxytocinergic and decreased vasopressinergic functions remains to be defined.
Esther Breslow - One of the best experts on this subject based on the ideXlab platform.
-
identification and observation of alkyl proton resonances of the amino terminal residues of bovine Neurophysins evidence for conformational differences between Neurophysin i and Neurophysin ii
International Journal of Peptide and Protein Research, 2009Co-Authors: Susan T Lord, Esther BreslowAbstract:Analysis of the 220 MHz proton magnetic resonance spectra of bovine Neurophysins-I and -II and of the effects of pH and succinylation of these spectra has allowed identification of the -CH3 proton resonances of the amino-terminal alanine of both proteins and of the -CH3 resonances of methionine-2 of Neurophysin-II. The alanine -CH3 resonance of Neurophysin-I is a sharp doublet at all pH values between 1 and 10.5 indicating relatively few restrictions on its mobility. By contrast, the -CH3 resonances of the amino-terminal alanine and methionine-2 of Neurophysin-II undergo pH-dependent changes in broadening compatible with the formation of an intramolecular salt-bridge at neutral pH between the protonated alpha-amino and an unprotonated side chain carboxyl. The results suggest that differeces in the properties of the two proteins are partially mediated by conformational differences involving their amino-terminal sequences. The potential usefulness of the amino-terminal resonances as n.m.r. 'reporter' signals is additionally demonstrated by studies of the effects of spin labels on the Neurophysin-I amino-terminal alanine resonance; these studies place the amino-terminus of Neurophysin-I approximately 14 A from residue 3 of peptides bound to the strong Neurophysin hormone-binding site.
-
binding and spectroscopic properties of ostrich Neurophysins probing the role of residue 35 at the monomer monomer interface
International Journal of Peptide and Protein Research, 2009Co-Authors: Esther Breslow, Thirleen Laborde, Hesta S. Saayman, Willem Oelofsen, Ryno J. NaudéAbstract:Binding and spectroscopic properties of ostrich Neurophysins were examined with emphasis on the behavior of Tyr-35, a residue that provides a potential probe of the monomer-monomer interface and of allosteric interrelationships between this region and the binding site. Mesotocin-associated ostrich Neurophysin was found to bind oxytocin and related peptides with affinities comparable to the mammalian proteins, but induced a significantly different optical activity in bound peptides than the mammalian proteins. Gel-filtration studies indicated higher dimerization constants for the ostrich Neurophysins than for the bovine Neurophysins. Consistent with this, Tyr-35 was found to be largely buried, as monitored by tyrosine titration and lack of reactivity towards tetranitromethane under non-denaturing conditions. Reaction of Tyr-35 of the mesotocin-associated protein with tetranitromethane under denaturing conditions, followed by refolding, allowed isolation of an active product with an altered interface region as partially evidenced by its titration properties and consistent with its markedly altered CD spectrum. Comparison of the CD spectra of the modified and native proteins and analysis of pH effects indicated the contribution of Tyr-35 to an unusual 237 nm band in the mesotocin-associated protein. Small shifts in the 350 nm CD band of nitrated Tyr-35 on binding peptide and apparent effects of nitration on the induced optical activity in bound peptide provided evidence of at least weak structural communication between Tyr-35 and the binding site. However, no significant effect of nitration on binding affinity was observed, suggesting that, in the mesotocin-associated protein, the region around residue 35 is not a stringent modulator of the thermodynamic behavior of the binding site.
-
Contributions of the interdomain loop, amino terminus, and subunit interface to the ligand-facilitated dimerization of Neurophysin: crystal structures and mutation studies of bovine Neurophysin-I.
Protein Science, 2006Co-Authors: Hunjoong Lee, Esther BreslowAbstract:Current evidence indicates that the ligand-facilitated dimerization of Neurophysin is mediated in part by dimerization-induced changes at the hormone binding site of the unliganded state that increase ligand affinity. To elucidate other contributory factors, we investigated the potential role of Neurophysin's short interdomain loop (residues 55–59), particularly the effects of loop residue mutation and of deleting amino-terminal residues 1–6, which interact with the loop and adjacent residues 53–54. The Neurophysin studied was bovine Neurophysin-I, necessitating determination of the crystal structures of des 1–6 bovine Neurophysin-I in unliganded and liganded dimeric states, as well as the structure of its liganded Q58V mutant, in which peptide was bound with unexpectedly increased affinity. Increases in dimerization constant associated with selected loop residue mutations and with deletion of residues 1–6, together with structural data, provided evidence that dimerization of unliganded Neurophysin-I is constrained by hydrogen bonding of the side chains of Gln58, Ser56, and Gln55 and by amino terminus interactions, loss or alteration of these hydrogen bonds, and probable loss of amino terminus interactions, contributing to the increased dimerization of the liganded state. An additional intersubunit hydrogen bond from residue 81, present only in the liganded state, was demonstrated as the largest single effect of ligand binding directly on the subunit interface. Comparison of bovine Neurophysins I and II indicates broadly similar mechanisms for both, with the exception in Neurophysin II of the absence of Gln55 side chain hydrogen bonds in the unliganded state and a more firmly established loss of amino terminus interactions in the liganded state. Evidence is presented that loop status modulates dimerization via long-range effects on Neurophysin conformation involving neighboring Phe22 as a key intermediary.
-
NMR investigation of main-chain dynamics of the H80E mutant of bovine Neurophysin-I: demonstration of dimerization-induced changes at the hormone-binding site.
Biochemistry, 2005Co-Authors: Mandar T. Naik, Hunjoong Lee, Clay Bracken, Esther BreslowAbstract:Neurophysins are hormone-binding proteins composed of two partially homologous domains. Ligand-binding (localized to the amino domain) and dimerization (involves both domains) are cooperatively linked by an as yet undefined allosteric mechanism. To help define this mechanism, we investigated the backbone dynamics of the unliganded monomeric state of the H80E mutant of bovine Neurophysin-I by 15N NMR. Model-free analysis of the NMR relaxation parameters indicated significantly greater flexibility in the carboxyl domain than in the amino domain, particularly at their dimerization interface segments. Amino domain residues critical to hormone binding were highly structured, constraining potential allosteric mechanisms. Model-free analysis additionally demonstrated chemical exchange effects, manifest as Rex terms, in 16 residues, 14 of which are located in the amino domain at, or immediately adjacent to, either the dimerization interface or the hormone-binding site. The chemical exchange process was further ch...
-
Slowly interchanging conformers of bovine Neurophysin-I in the unliganded dimeric state.
Biochemistry, 1992Co-Authors: Esther Breslow, P. K. Mishra, Hsien-bin Huang, Askel Bothner-byAbstract:The effect of Neurophysin dimerization on Tyr-49, a residue adjacent to the hormone-binding site, was investigated by proton NMR in order to analyze the basis of the dimerization-induced increase in Neurophysin hormone affinity. Dimerization-induced changes in Tyr-49 resonances, in two unliganded bovine Neurophysins, suggested that Tyr-49 perturbation is an intrinsic consequence of dimerization, although Tyr-49 is distant from the monomer-monomer interface in the crystalline liganded state. To determine whether this perturbation reflects a conformational difference between liganded and unliganded states that places Tyr-49 at the interface in the unliganded state, or a dimerization-induced change in secondary (2 degrees) or tertiary (3 degrees) structure, the more general structural consequences of dimerization were further analyzed. No change in 2 degrees structure upon dimerization was demonstrable by CD. On the other hand, a general similarity of regions involved in dimerization in unliganded and liganded states was indicated by NMR evidence of participation of His-80 and Phe-35 in dimerization in the unliganded state; both residues are at the interface in the crystal structure and distant from Tyr-49. Consistent with a lack of direct participation of Tyr-49 at the monomer-monomer interface, dimerization induced at least two distinct slowly exchanging environmental states for the 3.5 ring protons of Tyr-49 without significantly increased dipolar broadening relative to the monomer. Two environments were also found in the dimer of des-1-8 Neurophysin-I for the methyl protons of Thr-9, another residue distant from the monomer-monomer interface and close to the binding site in the liganded state.(ABSTRACT TRUNCATED AT 250 WORDS)
Jean-jacques Legros - One of the best experts on this subject based on the ideXlab platform.
-
avp and ot Neurophysins response to apomorphine and clonidine in major depression
Psychoneuroendocrinology, 2005Co-Authors: Gabrielle Scantamburlo, Sonia Fuchs, Michel Hansenne, Jean Reggers, Emmanuel Pinto, William Pitchot, Marc Ansseau, Jean-jacques LegrosAbstract:A number of studies have reported abnormalities of neurohypophyseal secretions in major depressive disorder. The purpose of the present study was to test the influence of apomorphine and clonidine injections on plasma vasopressin (AVP)-Neurophysins and oxytocin(OT)-Neurophysins levels, as direct index of posterior pituitary activation in major depression. Apomorphine and clonidine tests were carried out in 25 medication-free depressive patients and 25 age and gender-matched healthy controls. Blood for Neurophysins analysis was drawn by venipuncture at t0, t+20, t+40, t+60 and t+120. Baseline AVP-Neurophysins concentrations were significantly lower in depressives (0.12±0.14 ng/ml) than in healthy subjects (0.24±2.15 ng/ml) (p<0.04). The response to apomorphine test revealed a significant reduced response at 20 (p=0.01), 40 (p=0.007) and 60 (p=0.02) and 120 (p=0.02) min. Following clonidine test, post hoc tests also revealed a significant decrease at 0 (p=0.04), 20 (p=0.01), 40 (p=0.007) and 60 (p=0.02) and 120 (p=0.006) min. Concerning OT-Neurophysins, no significant differences were found between depressed and controls in response to clonidine or apomorphine injections. Following clonidine and apomorphine, major depressives exhibited a significantly lower peak GH response than controls. The study supports partially the hypothesis of a reduced vasopressinergic activity in depression. Moreover, we did not find any influence of acute apomorphine or clonidine injections on vasopressin-Neurophysin or oxytocin-Neurophysin in depressive patients.
-
apomorphine stimulation of vasopressin and oxytocin Neurophysins evidence for increased oxytocinergic and decreased vasopressinergic function in schizophrenics
Psychoneuroendocrinology, 1992Co-Authors: Jean-jacques Legros, C Gazzotti, T Carvelli, M Timsitberthier, Remy Frenckell, Paul Franchimont, Marc AnsseauAbstract:Abstract Apomorphine challenge tests (0.5 mg SC) were performed in 14 normal male volunteers and in 9 male schizophrenic inpatients, drug-free for at least 2 wk. In the normal volunteers, apomorphine induced an increase of serum growth hormone (GH) (maximum at 40 min), of vasopressin-Neurophysin (hN P I) (maximum at 20 min), and oxytocin-Neurophysin (hN P II) (maximum at 20 min). The release of Neurophysins was independent of digestive side effects. In the schizophrenics, the GH level and release pattern were similar to those in the controls. The basal level of hN P I was reduced (t 0 : 0.42±0.1 ng/ml in the schizophrenics and 0.66±0.05 ng/ml in the controls, p P II was increased (3.34 ± 0.04 ng / ml in the schizophrenics to 0.92±0.21 ng/ml in the controls, p =0.001). The response to apomorphine was blunted, with no significant release of hN P I or of hN P II. Although the hN P II data are consistent with an increased dopaminergic tone, the psychopathological meaning of the increased basal oxytocinergic and decreased vasopressinergic functions remains to be defined.