title: Phosphatidylinositol is involved in the membrane attachment of NCAM-120, the smallest component of the neural cell adhesion molecule.
abstract: The rodent neural cell adhesion molecule (NCAM) consists of three glycoproteins with Mr of 180,000, 140,000 and 120,000. The Mr 120,000 protein (NCAM-120) has been shown to exist in membrane-bound and soluble forms but the nature of its membrane association and release has remained obscure. We show here that phosphatidylinositol-specific phospholipase C (PI-PLC), but not a phospholipase C of different specificity, releases a substantial proportion of NCAM-120 from brain membranes and solubilizes almost quantitatively NCAM-120 present at the surface of C6 astroglial cells. The PI-PLC effect was highly selective since only one other protein species was detectably released from C6 cells. These results suggest that NCAM-120 is held in the membrane by covalently bound phosphatidylinositol or a closely related lipid in a way similar to several other surface proteins from eukaryotic cells. The presence of NCAM in a form which can be released from the cell surface by a highly selective mechanism raises additional possibilities for modulation and control of cell--cell adhesion.
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000378:metabolism*; D001921:Brain / Q000378:metabolism; D015815:Cell Adhesion Molecules; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism*; D008861:Microsomes / Q000378:metabolism; D010716:Phosphatidylinositols / Q000502:physiology*; D011485:Protein Binding; D051381:Rats; D010738:Type C Phospholipases / Q000494:pharmacology
chemical_list: D000954:Antigens, Surface; D015815:Cell Adhesion Molecules; D010716:Phosphatidylinositols; D010738:Type C Phospholipases