The Experts below are selected from a list of 8163 Experts worldwide ranked by ideXlab platform

Jin-ichi Inokuchi - One of the best experts on this subject based on the ideXlab platform.

  • GM3 Synthase (ST3Gal5) and Diabetes
    Glycoscience: Biology and Medicine, 2021
    Co-Authors: Jin-ichi Inokuchi
    Abstract:

    Ganglioside GM3 has been known to participate in insulin signaling by regulating the association of insulin receptor in caveolae Microdomains (lipid rafts). Studies on the molecular pathogenesis of type 2 diabetes and insulin resistance focusing on the interaction between insulin receptor and GM3 in adipocytes lead to a working hypothesis “metabolic disorders, such as type 2 diabetes, are Membrane Microdomain disorders caused by aberrant expression of gangliosides.” It is expected the development of novel diagnosis of metabolic syndromeMetabolic syndrome by identifying the specific ganglioside species and a therapeutic strategy “Membrane Microdomain ortho-signaling therapy.”

  • A New Pathological Feature of Insulin Resistance and Type 2 Diabetes: Involvement of Ganglioside GM3 and Membrane Microdomains
    Sphingolipid Biology, 2020
    Co-Authors: Jin-ichi Inokuchi, Kazuya Kabayama, Takashige Sato, Yasuyuki Igarashi
    Abstract:

    Membrane Microdomains (lipid rafts), which are critical for proper compartmentalization of insulin signaling, also play a role in the pathogenesis of insulin resistance, and yet this role has not been investigated. Detergent-resistant Membrane Microdomains (DRMs), isolated in low density fractions, are rich in cholesterol, glycosphingolipids and various signaling molecules. TNFφ induces insulin resistance in type 2 diabetes, but its action mechanism is not fully understood. We found a selective increase in the acidic glycosphingolipid ganglioside GM3 in 3T3-L1 adipocytes treated with TNFφ, suggesting a specific function for GM3. We extended these in vitro observations to living animals using obese Zucker fa/fa rats and ob/ob mice, in which the GM3 synthase mRNA levels in the white adipose tissues are significantly higher than in their lean controls. In DRMs from TNFφ-treated 3T3-L1 adipocytes, GM3 levels were doubled those of normal adipocytes. Additionally, insulin receptor (IR) accumulations in DRMs were diminished, while caveolin and flotillin levels were unchanged. GM3 depletion counteracted the TNFφ-induced inhibition of IR accumulation into DRMs. Together, these findings provide compelling evidence an insulin metabolic signaling defect can be attributed to a loss of IRs in the Microdomains due to an accumulation of GM3. Therefore, it is likely that life-style related diseases, such as type 2 diabetes, are Membrane Microdomain disorders caused by aberrant expression of glycosphingolipids.

  • GM3 and diabetes
    Glycoconjugate Journal, 2014
    Co-Authors: Jin-ichi Inokuchi
    Abstract:

    We demonstrated the molecular pathogenesis of type 2 diabetes and insulin resistance focusing on the interaction between insulin receptor and GM3 ganglioside in adipocytes and propose a working hypothesis “metabolic disorders, such as type 2 diabetes, are Membrane Microdomain disorders caused by aberrant expression of gangliosides”. It is expected that the development of novel diagnosis of metabolic syndrome by identifying the specific ganglioside species and a therapeutic strategy “Membrane Microdomain ortho-signaling therapy”.

  • Membrane Microdomains and insulin resistance.
    FEBS Letters, 2009
    Co-Authors: Jin-ichi Inokuchi
    Abstract:

    A new concept, that "metabolic disorders, such as type 2 diabetes, are Membrane Microdomain disorders caused by aberrant expression of gangliosides", has arisen. By examining this working hypothesis, we demonstrate the molecular pathogenesis of type 2 diabetes and insulin resistance focusing on the interaction between insulin receptor and gangliosides in Microdomains and propose the new therapeutic strategy "Membrane Microdomain ortho-signaling therapy".

  • insulin resistance as a Membrane Microdomain disorder
    Yakugaku Zasshi-journal of The Pharmaceutical Society of Japan, 2007
    Co-Authors: Jin-ichi Inokuchi
    Abstract:

    Membrane Microdomains (lipid rafts) are now recognized as critical for proper compartmentalization of insulin signaling, but their role in the pathogenesis of insulin resistance has not been investigated. Detergent-resistant Membrane Microdomains (DRMs), isolated in the low density fractions, are highly enriched in cholesterol, glycosphingolipids and various signaling molecules. TNFα induces insulin resistance in type 2 diabetes, but its mechanism of action is not fully understood. We have found a selective increase in the acidic glycosphingolipid ganglioside GM3 in 3T3-L1 adipocytes treated with TNFα, suggesting a specific function for GM3. We were able to extend these in vitro observations to living animals using obese Zucker fa/fa rats and ob/ob mice, in which the GM3 synthase mRNA levels in the white adipose tissues are significantly higher than in their lean controls. In the DRMs from TNFα-treated 3T3-L1 adipocytes, GM3 levels were doubled, compared to results in normal adipocytes. Additionally, insulin receptor (IR) accumulations in the DRMs were diminished, while caveolin and flotillin levels were unchanged. GM3 depletion was able to counteract the TNFα-induced inhibition of IR accumulation into DRMs. Together, these findings provide compelling evidence that in insulin resistance the insulin metabolic signaling defect can be attributed to a loss of IRs in the Microdomains due to an accumulation of GM3.

Shohei Maekawa - One of the best experts on this subject based on the ideXlab platform.

  • interaction of dynamin i with nap 22 a neuronal protein enriched in the presynaptic region
    Neuroscience Letters, 2018
    Co-Authors: Satoko Ueno, Mitsuhiro Morita, Hiroshi Miyoshi, Yoko Maruyama, Shohei Maekawa
    Abstract:

    Abstract Neurons have well-developed Membrane Microdomains called “rafts” that are recovered as a detergent-resistant low-density Membrane Microdomain fraction (DRM). NAP-22 is one of the major protein components of neuronal DRM and localizes in the presynaptic region. In order to know the role of NAP-22 in the synaptic transmission, NAP-22 binding proteins in the cytosol were searched with an affinity screening with NAP-22 as a bait and several protein bands were detected. Using mass-analysis and western blotting, one of the main band of ∼90 kDa was identified as dynamin I. The GTPase activity of dynamin I was partly inhibited by NAP-22 expressed in bacteria and this inhibition was recovered by the addition of calmodulin, a NAP-22 binding protein. The GTPase activity of dynamin was known to be activated with acidic Membrane lipids such as phosphatidylserine and the addition of NAP-22, a phosphatidylserine binding protein, inhibited the activation of the GTPase by this lipid. Since NAP-22 localizes on the presynaptic plasma Membrane and on synaptic vesicles, these results suggest the participation of NAP-22 in the Membrane cycling through binding to dynamin and acidic Membrane lipids at the presynaptic region.

  • ganglioside contained in the neuronal tissue enriched acidic protein of 22 kda nap 22 fraction prepared from the detergent resistant Membrane Microdomain of rat brain inhibits the phosphatase activity of calcineurin
    Journal of Neuroscience Research, 2015
    Co-Authors: Yuumi Kobayashi, Chihiro Sato, Ken Kitajima, Haruko Kumanogoh, Shun Nakamura, Ronan Da Silva, Shinji Miyata, Mistuhiro Morita, Fumio Hayashi, Shohei Maekawa
    Abstract:

    Neurons have well-developed Membrane Microdomains called “rafts” that are recovered as a detergent-resistant Membrane Microdomain fraction (DRM). Neuronal tissue-enriched acidic protein of 22 kDa (NAP-22) is one of the major protein components of neuronal DRM. To determine the cellular function of NAP-22, interacting proteins were screened with an immunoprecipitation assay, and calcineurin (CaN) was detected. Further studies with NAP-22 prepared from DRM and CaN expressed in bacteria showed the binding of these proteins and a dose-dependent inhibitory effect of the NAP-22 fraction on the phosphatase activity of CaN. On the other hand, NAP-22 expressed in bacteria showed low binding to CaN and a weak inhibitory effect on phosphatase activity. To solve this discrepancy, identification of a nonprotein component that modulates CaN activity in the DRM-derived NAP-22 fraction was attempted. After lyophilization, a lipid fraction was extracted with chloroform/methanol. The lipid fraction showed an inhibitory effect on CaN without NAP-22, and further fractionation of the extract with thin-layer chromatography showed the presence of several lipid bands having an inhibitory effect on CaN. The mobility of these bands coincided with that of authentic ganglioside (GM1a, GD1a, GD1b, and GT1b), and authentic ganglioside showed an inhibitory effect on CaN. Treatment of lipid with endoglycoceramidase, which degrades ganglioside to glycochain and ceramide, caused a diminution of the inhibitory effect. These results show that DRM-derived NAP-22 binds several lipids, including ganglioside, and that ganglioside inhibits the phosphatase activity of CaN. © 2015 Wiley Periodicals, Inc.

  • lipid components in the detergent resistant Membrane Microdomain drm obtained from the synaptic plasma Membrane of rat brain
    Neuroscience Letters, 2007
    Co-Authors: Daisuke Matsuura, Katsutoshi Taguchi, Hitoshi Yagisawa, Shohei Maekawa
    Abstract:

    Abstract Lateral association of sphingolipids and cholesterol is considered to form Membrane Microdomains such as “lipid rafts” obtainable as a detergent-resistant Membrane Microdomain (DRM) fraction after solubilization with a non-ionic detergent and density gradient centrifugation. Since not only sphinogolipids and cholesterol, but also functional lipids such as phosphatidylinositol 4,5-bisphosphate (PIP 2 ) are reported to be localized in DRM prepared from several cultured cells, this domain is considered to be a platform mediating lipid-signaling. Although PIP 2 is considered to have pivotal roles in the nervous system, little information is available on the localization of PIP 2 in the DRM within the synaptic plasma Membrane (SPM) obtained from matured rat brains. In this study, in order to know the localization of PIP 2 in SPM-derived DRM, we measured the amount of PIP 2 in SPM and SPM-derived DRM, by the thin-layer chromatography blotting method, using a GST-fusion protein of the pleckstrin-homology domain of phospholipase Cδ1 as a PIP 2 binding probe. About 10% of the PIP 2 in SPM was recovered in DRM. In contrast, over 40% recovery was observed for the Membrane cholesterol and sphingomyelin, and about 30% recovery was observed for phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine in the DRM were detected using the thin-layer chromatography method. Since the recovery of proteins in DRM was about 10%, the result indicates that there occurs no enrichment of PIP 2 in DRM prepared from SPM.

  • localization of phospholipase cβ1 on the detergent resistant Membrane Microdomain prepared from the synaptic plasma Membrane fraction of rat brain
    Journal of Neuroscience Research, 2007
    Co-Authors: Katsutoshi Taguchi, Haruko Kumanogoh, Shun Nakamura, Shohei Maekawa
    Abstract:

    The Membrane Microdomain (MD), such as detergent-resistant low-density Membrane Microdomain fraction (DRM), has been paid much attention because many signal-transducing molecules are recovered in this fraction, although precise localization and interactions of these molecules are largely unclear. To identify neuronal MD-localized proteins, monoclonal antibodies (mAbs) against the DRM-components of synaptic plasma Membrane fraction (SPM) were produced and the antigens were characterized. One of the antigens reacted with two closely positioned bands of about 140 kDa in SDS-PAGE and the antigen showed age-dependent localization on DRM. The antigen was immunoprecipitated with the mAb after partial solubilization with 0.6 M NaCl from SPM-derived DRM and identified as phospholipase Cβ1 through mass analysis. The identity was further confirmed with Western blotting using a specific polyclonal antibody. The enzyme purified from the DRM was activated by the α subunit of trimeric G protein, Gq, expressed in HEK293 cells. The lipid composition of the liposomes affected the enzymatic activity and the addition of NAP-22, a neuronal DRM-localized protein, inhibited the activity. These results suggest that there exists a signal-transducing MD that performs important roles in neuronal functions through PIP2 signaling and Ca2+ mobilization. © 2007 Wiley-Liss, Inc.

  • myelin protein zero is one of the components of the detergent resistant Membrane Microdomain fraction prepared from rat pituitary
    Journal of Molecular Histology, 2007
    Co-Authors: Katsutoshi Taguchi, Haruko Kumanogoh, Shun Nakamura, Seiji Miyata, Shohei Maekawa
    Abstract:

    Pituitary gland is a well-known endocrine tissue. The hypothalamo-neurohypophysial system, containing arginine vasopressin and oxytocin, shows a reversible morphological reorganization of both neurons and glial cells during chronic physiological stimulations. Since many signal transducing and cell adhesion molecules (CAMs) are recovered in Membrane Microdomain (MD) fractions, MDs are considered as signaling platforms of cells. In order to know the molecular background for these endocrine systems, we characterized MD-components derived from rat pituitary and found specific enrichment of several proteins in the fraction. One of them was identified as myelin protein zero (P0) with mass analysis and this result was further confirmed by a result that a specific antibody to this protein reacted to the authentic P0 protein in the myelin fraction of rat sciatic nerve. P0 is one of type-I transMembrane CAMs and a major structural component of mammalian peripheral nerve myelin. In mammals, expression of P0 has been considered to be restricted to peripheral nervous system. This result however indicates that P0 expresses more widely and its enrichment in the MD-fraction from rat pituitary suggests the participation in cell-cell communications.

Michelle M. Hill - One of the best experts on this subject based on the ideXlab platform.

  • raftprot v2 understanding Membrane Microdomain function through lipid raft proteomes
    Nucleic Acids Research, 2019
    Co-Authors: Michelle M. Hill, Ahmed Mohamed, Anup Shah, David Chen
    Abstract:

    Cellular Membranes feature dynamic submicrometer-scale lateral domains termed lipid rafts, Membrane rafts or glycosphingolipid-enriched Microdomains (GEM). Numerous proteomics studies have been conducted on the lipid raft proteome, however, interpretation of individual studies is limited by potential undefined contaminant proteins. To enable integrated analyses, we previously developed RaftProt (http://lipid-raft-database.di.uq.edu.au/), a searchable database of mammalian lipid raft-associated proteins. Despite being a highly used resource, further developments in annotation and utilities were required. Here, we present RaftProt V2 (http://raftprot.org), an improved update of RaftProt. Besides the addition of new datasets and re-mapping of all entries to both UniProt and UniRef IDs, we have implemented a stringent annotation based on experimental evidence level to assist in identification of possible contaminant proteins. RaftProt V2 allows for simultaneous search of multiple proteins/experiments at the cell/tissue type and UniRef/Gene level, where correlations, interactions or overlaps can be investigated. The web-interface has been completely re-designed to enable interactive data and subset selection, correlation analysis and network visualization. Overall, RaftProt aims to advance our understanding of lipid raft function through integrative analysis of datasets collected from diverse tissue and conditions. Database URL: http://raftprot.org.

  • raftprot v2 understanding Membrane Microdomain function through lipid raft proteomes
    bioRxiv, 2018
    Co-Authors: Ahmed Mohamed, Anup Shah, David Chen, Michelle M. Hill
    Abstract:

    Cellular Membranes feature dynamic submicrometer-scale lateral Membrane domainsvariously referred to as lipid rafts, Membrane rafts or glycosphingolipid-enriched Microdomains (GEM). In order to understand the molecular functions of lipid rafts, numerous studies have utilized various biochemical methods to isolate and examine the protein composition of Membrane rafts. However, interpretation of individual raft proteomics studies are confounded by the limitations of isolation methods and the dynamic nature of rafts. Knowledge-based approaches can facilitate biological data interpretation by integrating experimental evidence from existing studies. To this end, we previously developed RaftProt (http://lipid-raft-database.di.uq.edu.au/), a searchable database of mammalian lipid raft-associated proteins. Despite being a valuable and highly used resource, improvements in search capabilities and visualisation were still needed. Here, we present RaftProt V2 (http://raftprot.org), an improved update of RaftProt, enabling interrogation and integration of datasets at the cell/tissue type and UniRef/Gene level. Besides the addition of new datasets and re-mapping of all entries to both UniProt and UniRef IDs, we have annotated the level of experimental evidence for each protein entry. The search engine now allows for multiple protein or experiment searches where correlations, interactions or overlaps can be investigated. The web-interface has been completely re-designed and offers new interactive tools for data and subset selection, correlation analysis and network visualization. Overall, RaftProt aims to advance our understanding of lipid raft function by revealing the proteomes and pathways that are associated with Membrane Microdomains in diverse tissue and conditions. Database URL: http://raftprot.org

  • Ripples in the pond--using a systems approach to decipher the cellular functions of Membrane Microdomains.
    Molecular BioSystems, 2013
    Co-Authors: Kerry L. Inder, Melissa J. Davis, Michelle M. Hill
    Abstract:

    Membrane Microdomains such as lipid rafts and caveolae regulate a myriad of cellular functions including cell signalling, protein trafficking, cell viability, and cell movement. They have been implicated in diseases such as cancer, diabetes and Alzheimer's disease, highlighting the essential role they play in cell processes. Despite much research and debate on the size, composition and dynamics of Membrane Microdomains, the molecular mechanism(s) of their action remain poorly understood. Most studies have dealt solely with the content and properties of the Membrane Microdomain as an entity in itself. However, recent work shows that Membrane Microdomain disruption has wide ranging effects on other subcellular compartments, and the cell as a whole. Hence we propose that a systems approach incorporating many cellular attributes such as subcellular localisation is required in order to understand the global impact of Microdomains on cell function. Although analysis of sub-proteome changes already provides additional insight, we further propose biological network analysis of functional proteomics data to capture effects at the systems level. In this review, we highlight the use of protein–protein interactions networks and mixed networks to portray and visualize the relationships between proteins within and between subcellular fractions. Such a systems analysis will be required to improve our understanding of the full cellular function of Membrane Microdomains.

Ahmed Mohamed - One of the best experts on this subject based on the ideXlab platform.

  • raftprot v2 understanding Membrane Microdomain function through lipid raft proteomes
    Nucleic Acids Research, 2019
    Co-Authors: Michelle M. Hill, Ahmed Mohamed, Anup Shah, David Chen
    Abstract:

    Cellular Membranes feature dynamic submicrometer-scale lateral domains termed lipid rafts, Membrane rafts or glycosphingolipid-enriched Microdomains (GEM). Numerous proteomics studies have been conducted on the lipid raft proteome, however, interpretation of individual studies is limited by potential undefined contaminant proteins. To enable integrated analyses, we previously developed RaftProt (http://lipid-raft-database.di.uq.edu.au/), a searchable database of mammalian lipid raft-associated proteins. Despite being a highly used resource, further developments in annotation and utilities were required. Here, we present RaftProt V2 (http://raftprot.org), an improved update of RaftProt. Besides the addition of new datasets and re-mapping of all entries to both UniProt and UniRef IDs, we have implemented a stringent annotation based on experimental evidence level to assist in identification of possible contaminant proteins. RaftProt V2 allows for simultaneous search of multiple proteins/experiments at the cell/tissue type and UniRef/Gene level, where correlations, interactions or overlaps can be investigated. The web-interface has been completely re-designed to enable interactive data and subset selection, correlation analysis and network visualization. Overall, RaftProt aims to advance our understanding of lipid raft function through integrative analysis of datasets collected from diverse tissue and conditions. Database URL: http://raftprot.org.

  • raftprot v2 understanding Membrane Microdomain function through lipid raft proteomes
    bioRxiv, 2018
    Co-Authors: Ahmed Mohamed, Anup Shah, David Chen, Michelle M. Hill
    Abstract:

    Cellular Membranes feature dynamic submicrometer-scale lateral Membrane domainsvariously referred to as lipid rafts, Membrane rafts or glycosphingolipid-enriched Microdomains (GEM). In order to understand the molecular functions of lipid rafts, numerous studies have utilized various biochemical methods to isolate and examine the protein composition of Membrane rafts. However, interpretation of individual raft proteomics studies are confounded by the limitations of isolation methods and the dynamic nature of rafts. Knowledge-based approaches can facilitate biological data interpretation by integrating experimental evidence from existing studies. To this end, we previously developed RaftProt (http://lipid-raft-database.di.uq.edu.au/), a searchable database of mammalian lipid raft-associated proteins. Despite being a valuable and highly used resource, improvements in search capabilities and visualisation were still needed. Here, we present RaftProt V2 (http://raftprot.org), an improved update of RaftProt, enabling interrogation and integration of datasets at the cell/tissue type and UniRef/Gene level. Besides the addition of new datasets and re-mapping of all entries to both UniProt and UniRef IDs, we have annotated the level of experimental evidence for each protein entry. The search engine now allows for multiple protein or experiment searches where correlations, interactions or overlaps can be investigated. The web-interface has been completely re-designed and offers new interactive tools for data and subset selection, correlation analysis and network visualization. Overall, RaftProt aims to advance our understanding of lipid raft function by revealing the proteomes and pathways that are associated with Membrane Microdomains in diverse tissue and conditions. Database URL: http://raftprot.org

Katsutoshi Taguchi - One of the best experts on this subject based on the ideXlab platform.

  • lipid components in the detergent resistant Membrane Microdomain drm obtained from the synaptic plasma Membrane of rat brain
    Neuroscience Letters, 2007
    Co-Authors: Daisuke Matsuura, Katsutoshi Taguchi, Hitoshi Yagisawa, Shohei Maekawa
    Abstract:

    Abstract Lateral association of sphingolipids and cholesterol is considered to form Membrane Microdomains such as “lipid rafts” obtainable as a detergent-resistant Membrane Microdomain (DRM) fraction after solubilization with a non-ionic detergent and density gradient centrifugation. Since not only sphinogolipids and cholesterol, but also functional lipids such as phosphatidylinositol 4,5-bisphosphate (PIP 2 ) are reported to be localized in DRM prepared from several cultured cells, this domain is considered to be a platform mediating lipid-signaling. Although PIP 2 is considered to have pivotal roles in the nervous system, little information is available on the localization of PIP 2 in the DRM within the synaptic plasma Membrane (SPM) obtained from matured rat brains. In this study, in order to know the localization of PIP 2 in SPM-derived DRM, we measured the amount of PIP 2 in SPM and SPM-derived DRM, by the thin-layer chromatography blotting method, using a GST-fusion protein of the pleckstrin-homology domain of phospholipase Cδ1 as a PIP 2 binding probe. About 10% of the PIP 2 in SPM was recovered in DRM. In contrast, over 40% recovery was observed for the Membrane cholesterol and sphingomyelin, and about 30% recovery was observed for phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine in the DRM were detected using the thin-layer chromatography method. Since the recovery of proteins in DRM was about 10%, the result indicates that there occurs no enrichment of PIP 2 in DRM prepared from SPM.

  • localization of phospholipase cβ1 on the detergent resistant Membrane Microdomain prepared from the synaptic plasma Membrane fraction of rat brain
    Journal of Neuroscience Research, 2007
    Co-Authors: Katsutoshi Taguchi, Haruko Kumanogoh, Shun Nakamura, Shohei Maekawa
    Abstract:

    The Membrane Microdomain (MD), such as detergent-resistant low-density Membrane Microdomain fraction (DRM), has been paid much attention because many signal-transducing molecules are recovered in this fraction, although precise localization and interactions of these molecules are largely unclear. To identify neuronal MD-localized proteins, monoclonal antibodies (mAbs) against the DRM-components of synaptic plasma Membrane fraction (SPM) were produced and the antigens were characterized. One of the antigens reacted with two closely positioned bands of about 140 kDa in SDS-PAGE and the antigen showed age-dependent localization on DRM. The antigen was immunoprecipitated with the mAb after partial solubilization with 0.6 M NaCl from SPM-derived DRM and identified as phospholipase Cβ1 through mass analysis. The identity was further confirmed with Western blotting using a specific polyclonal antibody. The enzyme purified from the DRM was activated by the α subunit of trimeric G protein, Gq, expressed in HEK293 cells. The lipid composition of the liposomes affected the enzymatic activity and the addition of NAP-22, a neuronal DRM-localized protein, inhibited the activity. These results suggest that there exists a signal-transducing MD that performs important roles in neuronal functions through PIP2 signaling and Ca2+ mobilization. © 2007 Wiley-Liss, Inc.

  • myelin protein zero is one of the components of the detergent resistant Membrane Microdomain fraction prepared from rat pituitary
    Journal of Molecular Histology, 2007
    Co-Authors: Katsutoshi Taguchi, Haruko Kumanogoh, Shun Nakamura, Seiji Miyata, Shohei Maekawa
    Abstract:

    Pituitary gland is a well-known endocrine tissue. The hypothalamo-neurohypophysial system, containing arginine vasopressin and oxytocin, shows a reversible morphological reorganization of both neurons and glial cells during chronic physiological stimulations. Since many signal transducing and cell adhesion molecules (CAMs) are recovered in Membrane Microdomain (MD) fractions, MDs are considered as signaling platforms of cells. In order to know the molecular background for these endocrine systems, we characterized MD-components derived from rat pituitary and found specific enrichment of several proteins in the fraction. One of them was identified as myelin protein zero (P0) with mass analysis and this result was further confirmed by a result that a specific antibody to this protein reacted to the authentic P0 protein in the myelin fraction of rat sciatic nerve. P0 is one of type-I transMembrane CAMs and a major structural component of mammalian peripheral nerve myelin. In mammals, expression of P0 has been considered to be restricted to peripheral nervous system. This result however indicates that P0 expresses more widely and its enrichment in the MD-fraction from rat pituitary suggests the participation in cell-cell communications.

  • localization of the cl atpase activity on nap 22 enriched Membrane Microdomain raft of rat brain
    Neuroscience Letters, 2004
    Co-Authors: Shohei Maekawa, Katsutoshi Taguchi
    Abstract:

    Abstract Much attention has been paid to the Membrane Microdomain enriched in cholesterol and sphingolipids called raft. In the central nervous system, however, the physiological role of this domain is not so evident at present, partly because of the complexity of the protein components in the raft fraction. In this study we surveyed ATPase activities in the raft fraction obtained from the synaptic plasma Membrane of rat brain and found the enrichment of an ethacrynic acid-sensitive ATPase (Cl−-pump) activity. Immunoprecipitation experiments using antibodies to raft-localized proteins showed the co-precipitation of the ATPase activity with NAP-22, a major raft-localized protein. This result suggests the participation of the raft in the regulation of ion transport in addition to the presence of heterogeneity of raft domains in neurons.