Identification of the specific labile sites in the 180 kDa catalytic polypeptide of the Drosophila melanogaster DNA polymerase alpha-primase complex.
The immunoaffinity-purified DNA polymerase alpha-primase complex from Drosophila melanogaster Kc cells contains three high molecular weight polypeptides besides the 180 kDa catalytic polypeptide. These polypeptides are immunologically cross-reactive with the 180 kDa polypeptide. When the immunoaffinity-purified complex was kept at 4 degrees C for about four weeks, the amounts of the three polypeptides increased, while the 180 kDa polypeptide completely disappeared. Sodium bisulfite inhibited the decrease in the 180 kDa polypeptide. The N-terminal amino acid sequences of all the polypeptides were all assigned to ones present in a portion close to the N-terminus of the 180 kDa polypeptide. The N-terminal residue of all the three polypeptides was Ser. The cleavage sites were Phe130-Ser131, Thr180-Ser181, and Phe237-Ser238. These results show that the three polypeptides are cleavage products of the 180 kDa catalytic polypeptide, the cleavage occurring at specific labile sites including a Ser residue. The amino acid residues at the sites are quite different from those (Lys-Lys) in the human 180 kDa catalytic polypeptide.
Kuroda
K
K
Mitsubishi Kasei Institute of Life Sciences, Tokyo.
Kagiyama-Takahashi
R
R
Okuda
A
A
Omori
A
A
D000595:Amino Acid Sequence; D000818:Animals; D002384:Catalysis; D002460:Cell Line; D019915:DNA Primase; D004331:Drosophila melanogaster; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments / Q000378:metabolism; D010455:Peptides / Q000378:metabolism; D012316:RNA Nucleotidyltransferases / Q000378:metabolism*
D010446:Peptide Fragments; D010455:Peptides; D019915:DNA Primase; D012316:RNA Nucleotidyltransferases