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Polycation‐dependent, Ca 2+ ‐antagonized phosphorylation of calmodulin by casein kinase‐2 and a spleen tyrosine protein kinase
Author(s) -
Meggio Flavio,
Brunati Anna Maria,
Pinna Lorenzo A.
Publication year - 1987
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(87)80154-0
Subject(s) - calmodulin , phosphorylation , protein kinase a , biochemistry , protein phosphorylation , tyrosine kinase , kinase , chemistry , casein kinase 2 , tyrosine , casein , tyrosine phosphorylation , mitogen activated protein kinase kinase , biology , microbiology and biotechnology , enzyme , signal transduction
Ten distinct protein kinases have been tested for their ability to phosphorylate calmodulin. Only casein kinase‐2 and a spleen tyrosine protein kinase (TPK‐III) proved effective, their phosphorylation efficiency being dramatically enhanced by histones and other polybasic peptides while being depressed by 50 μM Ca 2+ . Phosphorylation by CK‐2 takes place with a K m of 12 μM calmodulin, leading to the incorporation of more than 1.5 mol P/mol substrate. Ser 81 and Thr 79 are among the residues affected. On the other hand, the two tyrosyl residues of calmodulin are both phosphorylated by TPK‐III, Tyr 99 being preferred over Tyr 138 .