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Phosphorylation of rat brain calpastatins by protein kinase C
Author(s) -
Averna M.,
De Tullio R.,
Salamino F.,
Melloni E.,
Pontremoli S.
Publication year - 1999
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/s0014-5793(99)00461-5
Subject(s) - calpastatin , calpain , phosphorylation , serine , kinase , protein kinase a , chemistry , biochemistry , mitogen activated protein kinase kinase , microbiology and biotechnology , biology , enzyme
Calpastatin, the natural inhibitor of calpain, is present in rat brain in multiple forms, having different molecular masses, due to the presence of one (low Mr form) or four (high Mr form) repetitive inhibitory domains. Recombinant and native calpastatin forms are substrates of protein kinase C, which phosphorylates a single serine residue at their N‐terminus. Furthermore, both low and high Mr calpastatins are phosphorylated by protein kinase C at the same site. These calpastatin forms are phosphorylated also by protein kinase A, although with a lower efficiency. The incorporation of a phosphate group determines an increase in the concentration of Ca 2+ required to induce the formation of the calpain‐calpastatin complex. This effect results in a large decrease of the inhibitory efficiency of calpastatins. We suggest that phosphorylation of calpastatin represents a mechanism capable to balance the actual amount of active calpastatin to the level of calpain to be activated.