A NOVEL PHOSPHATIDYLSERINE-BINDING PEPTIDE MOTIF DEFINED BY AN ANTIIDIOTYPIC MONOCLONAL-ANTIBODY - LOCALIZATION OF PHOSPHATIDYLSERINE-SPECIFIC BINDING-SITES ON PROTEIN-KINASE-C AND PHOSPHATIDYLSERINE DECARBOXYLASE

A monoclonal anti-idiotypic antibody, Id8F7, previously shown to bind to a phosphatidylserine (PS)-specific binding site on protein kinase C (PKC) has been used to identify a 12-amino acid consensus sequence sh ared by PKC and phosphatidylserine decarboxylase (PSD). The 14-amino a cid synthetic peptide derived from the corresponding region of PSD (am ino acids 351-364 of the enzyme from Chinese hamster ovary cells) boun d effectively and specifically to PS, and that derived from rat PKC ga mma (amino acids 227-240) bound weakly but specifically to PS. Analysi s of binding of Id8F7 to various synthetic peptides revealed that the consensus sequence motif, FXFXLKXXXKXR, is responsible for the interac tion with both Id8F7 and PS. The results suggest that the conserved am ino acid residues represent a basic structural motif for the specific interaction with PS, and the corresponding regions of PKC and PSD form the PS-specific binding sites of these enzymes.