Novel consensus sequence for the Golgi apparatus casein kinase, revealed using proline-rich protein-1 (PRP1)-derived peptide substrates.
Previous studies have shown that the Golgi apparatus casein kinase (G-CK) recognizes phosphoacceptor sites specified by the triplet SXE/Sp, which is found in several phosphoproteins, besides casein itself. In the present study, we report that G-CK can phosphorylate, with comparable efficiency, sequences surrounding Ser-22 of salivary proline-rich protein-1 (PRP1), which do not conform to the SXE/Sp motif. By using a series of peptide substrates derived from the PRP1 Ser-22 site, we also have shown that the optimal consensus sequence recognized by G-CK in this case was SXQXX(D/E)3, where the acidic residues at positions n+5 to n+7 and, to a lesser extent, the glutamine residue at position n+2 are the critical determinants.
Brunati
A M
AM
Dipartimento di Chimica Biologica, Centro per lo Studio delle Biomembrane del CNR and CRIBI, Università degli Studi di Padova, Viale G. Colombo 3, 35121 Padova, Italy.
Marin
O
O
Bisinella
A
A
Salviati
A
A
Pinna
L A
LA
D000595:Amino Acid Sequence; D047388:Casein Kinases; D016384:Consensus Sequence; D006056:Golgi Apparatus / Q000201:enzymology*; D007700:Kinetics; D008969:Molecular Sequence Data; D010455:Peptides / Q000378:metabolism*; D055232:Proline-Rich Protein Domains; D011494:Protein Kinases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D013379:Substrate Specificity
D010455:Peptides; D011494:Protein Kinases; D047388:Casein Kinases