title: Absence of TrkB and insulin receptor beta in the Triton insoluble low-density fraction (raft).
abstract: Cholesterol- and glycolipid-enriched microdomains within the plasma membrane of animal cells, including neurons, have been purified and used as a low-density membrane domain after extraction with Triton X-100 (raft), or after subcellular fractionation without detergent (LDM). In this study, we compared the protein compositions in the raft and the LDM. Membrane receptors, acylated- and glycosylphosphatidylinositol (GPI)- anchored proteins were enriched in the LDM. Further treatment of the LDM with Triton X-100 excluded the membrane receptors, TrkBs and insulin receptor beta. In the presence of calcium ions, the endogenous tyrosine kinase activities in the LDM and the raft were enhanced, suggesting an important role of calcium ions in the signal transduction via the LDM and the raft.
authors.affiliation: Department of Cellular and Molecular Biology, Primate Research Institute, Kyoto University, Inuyama, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ohira
authors.forename: S
authors.initials: S
authors.lastname: Maekawa
authors.forename: M
authors.initials: M
authors.lastname: Hayashi
mesh_terms: D000107:Acetylation; D000818:Animals; D015153:Blotting, Western; D001923:Brain Chemistry; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002458:Cell Fractionation; D004591:Electrophoresis, Polyacrylamide Gel; D017261:Glycosylphosphatidylinositols / Q000737:chemistry; D008562:Membrane Glycoproteins / Q000032:analysis* / Q000737:chemistry / Q000172:deficiency / Q000187:drug effects; D008970:Molecular Weight; D009419:Nerve Tissue Proteins / Q000737:chemistry; D017830:Octoxynol / Q000737:chemistry / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D019000:Phosphotyrosine / Q000032:analysis; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D051381:Rats; D011972:Receptor, Insulin / Q000032:analysis* / Q000172:deficiency; D011956:Receptors, Cell Surface / Q000737:chemistry; D012995:Solubility; D013347:Subcellular Fractions / Q000737:chemistry*; D014404:Tubulin / Q000032:analysis; D020813:Receptor, trkB
chemical_list: D002118:Calcium; D017261:Glycosylphosphatidylinositols; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D017830:Octoxynol; D019000:Phosphotyrosine; D011505:Protein-Tyrosine Kinases; D011972:Receptor, Insulin; D011956:Receptors, Cell Surface; D014404:Tubulin; C064371:Ntrk2 protein, mouse; D020813:Receptor, trkB