The localization of the cAMP-dependent protein kinase phosphorylation site in the platelet rat protein, rap 1B.
Rap 1B is a low molecular weight G protein which is phosphorylated by cAMP-dependent protein kinase. In order to identify the site of phosphorylation by cAMP-dependent protein kinase, purified rap 1B from human platelets was phosphorylated and subjected to limited proteolysis with trypsin. Single digestion fragment containing the phosphorylation site was obtained and purified by reversed-phase HPLC. Sequence analysis of the phosphorylated digestion fragment demonstrated that the sequence of the phosphorylation site was -Lys-Lys-Ser-Ser-. This sequence is near the carboxy terminus and is adjacent to the site of membrane attachment of the protein.
Fischer
T H
TH
Department of Medicine, University of North Carolina, Chapel Hill 27514.
Collins
J H
JH
Gatling
M N
MN
White
G C
GC
D000595:Amino Acid Sequence; D001792:Blood Platelets / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000097:blood* / Q000302:isolation & purification; D006801:Humans; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000302:isolation & purification; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D012689:Sequence Homology, Nucleic Acid; D014357:Trypsin; D020668:rap GTP-Binding Proteins
D010446:Peptide Fragments; D011494:Protein Kinases; D014357:Trypsin; D019204:GTP-Binding Proteins; D020668:rap GTP-Binding Proteins