Differentiation state-dependent surface mobilities of two forms of the neural cell adhesion molecule.
The neural cell adhesion molecule (N-CAM) has been implicated in morphogenetic events during formation of the nervous system. Three forms of N-CAM exist, all glycoprotein chains, of relative molecular masses 180,000 (180K), 140K and 120K (N-CAM180, N-CAM140 and N-CAM120) which are differentially expressed on neural cell types and during development. The three chains are thought to carry similar if not identical amino-acid sequences on their extracellular amino-terminal domains, but differ in the length of their carboxy-terminal cytoplasmic region. They occur in highly sialylated embryonic and less sialylated adult forms. N-CAM180 is selectively expressed in more differentiated neural cells and may play a role in the stabilization of cell contacts. To investigate this, we have studied in the surface membrane of a mouse neuroblastoma cell line N2A the lateral mobility of the two predominant forms of N-CAM, N-CAM180 and N-CAM140, as a function of differentiation. Here we report that as judged by fringe pattern photobleaching, the surface mobility of N-CAM140 is higher than that of N-CAM180, suggesting an association of N-CAM180 with the cytoskeleton or other stabilizing factors. We also show that brain spectrin, a membrane-cytoskeleton linker protein, binds only to N-CAM180. The immobilization of N-CAM in differentiated N2A cells is achieved by a shift in expression from N-CAM140 to N-CAM180.
D000818:Animals; D000906:Antibodies; D000936:Antigen-Antibody Complex; D000954:Antigens, Surface / Q000032:analysis*; D015815:Cell Adhesion Molecules; D002454:Cell Differentiation; D002455:Cell Division; D002460:Cell Line; D002462:Cell Membrane / Q000648:ultrastructure; D005455:Fluorescent Antibody Technique; D051379:Mice; D009447:Neuroblastoma / Q000473:pathology
D000906:Antibodies; D000936:Antigen-Antibody Complex; D000954:Antigens, Surface; D015815:Cell Adhesion Molecules