title: Amino acid sequences surrounding the cAMP-dependent and calcium/calmodulin-dependent phosphorylation sites in rat and bovine synapsin I.
abstract: The amino acid sequences surrounding three major phosphorylation sites in rat and bovine synapsin I have been determined by employing automated gas-phase sequencing and manual Edman degradation of purified phosphopeptide fragments. Site 1 is a serine residue phosphorylated by cAMP-dependent protein kinase and by calcium/calmodulin-dependent protein kinase I. The sequence around site 1 was derived from tryptic/chymotryptic phosphopeptides and overlapping cyanogen bromide cleavage fragments. This sequence, identical in rat and bovine synapsin I, is Asn-Tyr-Leu-Arg-Arg-Arg-Leu-Ser(P)-Asp-Ser-Asn-Phe-Met. Site 1 is located at the NH2 terminus of the protein, within the collagenase-resistant head region. Sites 2 and 3 are serine residues phosphorylated by calcium/calmodulin-dependent protein kinase II. The sequences surrounding bovine site 2 and site 3 were derived from tryptic phosphopeptides and overlapping fragments generated by cleavage with chymotrypsin, collagenase, and endoproteinase Lys-C. The sequence around bovine site 2 is Thr-Arg-Gln-Thr-Ser(P)-Val-Ser-Gly-Gln-Ala-Pro-Pro-Lys, and the sequence around bovine site 3 is Thr-Arg-Gln-Ala-Ser(P)-Gln-Ala-Gly-Pro-Met-Pro-Arg. Sites 2 and 3 are located within the COOH-terminal, collagenase-sensitive tail region of the molecule, separated by 36 amino acids. The sequences surrounding rat site 2 and site 3 were derived from tryptic phosphopeptides. The sequence around rat site 2 is Gln-Ala-Ser(P)-Ile-Ser-Gly-Pro-Ala-Pro-Pro-Lys, and the sequence around rat site 3 is Gln-Ala-Ser(P)-Gln-Ala-Gly-Pro-Gly-Pro-Arg. Thus, the sequences surrounding the four sites that are phosphorylated by calcium/calmodulin-dependent protein kinase II, namely sites 2 and 3 in rat and bovine synapsin I, exhibit a high degree of homology.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000378:metabolism; D002417:Cattle; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000302:isolation & purification / Q000378:metabolism*; D010449:Peptide Mapping; D010748:Phosphopeptides / Q000302:isolation & purification; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D051381:Rats; D012689:Sequence Homology, Nucleic Acid; D016704:Synapsins
chemical_list: D008869:Microtubule-Associated Proteins; D009419:Nerve Tissue Proteins; D010748:Phosphopeptides; D016704:Synapsins; D011494:Protein Kinases