CHARACTERIZATION OF PROTEIN-KINASE C-MEDIATED PHOSPHORYLATION OF THE SHORT CYTOPLASMIC DOMAIN ISOFORM OF C-CAM

C-CAM is a ubiquitously expressed cell adhesion molecule belonging to the carcinoembryonic antigen family, Two co-expressed isoforms, C-CAM- L and C-CAM-S, are known, having different cytoplasmic domains both of which can be phosphorylated in vivo. Here rye have characterized the PKC-mediated phosphorylation of the short cytoplasmic domain isoform, C-CAM-S. Phorbol myristyl acetate induced phosphorylation of C-CAM-S i n transfected CHO cells, Using synthetic peptides and Edman degradatio n we identified Ser(449) as the PKC-phosphorylated amino acid residue, Binding experiments with modified peptides indicated that this phosph orylation decreases the ability of the cytoplasmic domain of C-CAM-S t o bind calmodulin. (C) 1998 Federation of European Biochemical Societi es.