title: Solubility and posttranslational regulation of GP130/F11--a neuronal GPI-linked cell adhesion molecule enriched in the neuronal membrane skeleton.
abstract: GP130 (renamed contactin) has previously been identified by its detergent insolubility and retention with the actin-containing "membrane skeleton" isolated from chicken neurons and brain. The contactin sequence predicted a transmembrane and cytoplasmic domain for the molecule. Recently, F11 was shown to have an identical sequence except for the C terminus, and it was predicted to be linked to the plasma membrane by a glycosylphosphatidylinositol (GPI) group. Here we describe that GP130 can be released both from brain membranes and the detergent-insoluble membrane skeleton by a phosphoinositol-specific phospholipase C (PI-PLC) indicating that F11 and GP130/contactin are probably identical and that surprisingly the lipid anchor is partly or totally responsible for its non-ionic detergent insolubility. The "membrane skeleton" is a rich source of GPI-linked glycoproteins as judged by 1) most glycoproteins can be released by a PI-PLC and 2) most [3H]ethanolamine-labeled glycoproteins are present in, or enriched in the membrane skeleton. Thus, detergent insolubility appears to be a characteristic of GPI-anchored glycoproteins. No evidence has been obtained that GP130/F11 is released or secreted in vivo or in culture. In addition, GP130/F11 has an unusually long half-life in culture of greater than 3 days. The structure of the neuronal membrane skeleton and the potential function of GPI-anchored glycoproteins is discussed.
authors.affiliation: Department of Human Anatomy and Cell Biology, Liverpool, United Kingdom.
authors.forename: D J
authors.initials: DJ
authors.lastname: Moss
authors.forename: C A
authors.initials: CA
authors.lastname: White
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D001923:Brain Chemistry; D015820:Cadherins / Q000032:analysis / Q000096:biosynthesis*; D015815:Cell Adhesion Molecules / Q000096:biosynthesis; D015816:Cell Adhesion Molecules, Neuronal; D002462:Cell Membrane / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D002642:Chick Embryo; D058966:Contactins; D019856:Ethanolamine; D004983:Ethanolamines / Q000378:metabolism; D006017:Glycolipids / Q000032:analysis*; D017261:Glycosylphosphatidylinositols; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000096:biosynthesis*; D009474:Neurons / Q000737:chemistry / Q000378:metabolism*; D010716:Phosphatidylinositols / Q000032:analysis*; D011499:Protein Processing, Post-Translational; D012995:Solubility; D013564:Sympathetic Nervous System / Q000737:chemistry / Q000378:metabolism
chemical_list: D015820:Cadherins; D015815:Cell Adhesion Molecules; D015816:Cell Adhesion Molecules, Neuronal; D058966:Contactins; D004983:Ethanolamines; D006017:Glycolipids; D017261:Glycosylphosphatidylinositols; C099972:H-cadherin; D009419:Nerve Tissue Proteins; D010716:Phosphatidylinositols; D019856:Ethanolamine