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The localization of the cAMP‐dependent protein kinase phosphorylation site in the platelet rat protein, rap 1B
Author(s) -
Fischer Thomas H.,
Collins John H.,
Gatling Margaret N.,
White Gilbert C.
Publication year - 1991
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(91)80581-m
Subject(s) - phosphorylation , protein kinase a , proteolysis , biochemistry , protein phosphorylation , chemistry , trypsin , kinase , protein kinase c , microbiology and biotechnology , biology , enzyme
Rap1B 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 rap1B 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 carboxyl terminus and is adjacent to the site of membrane attachment of the protein.