Phosphatidylinositol is involved in the membrane attachment of NCAM-120, the smallest component of the neural cell adhesion molecule
He, H.T.; Barbet, J.; Chaix, J.C.; Goridis, C.
EMBO Journal 5(10): 2489-2494
1986
ISSN/ISBN: 0261-4189 PMID: 3780668 Document Number: 274430
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.