Phosphorylation of rat brain calpastatins by protein kinase C

FEBS Letters

De Tullio, R.¹  Pontremoli, S.¹  Salamino, F.¹  Averna, M.¹  Melloni, E.¹ 

[1] Department of Experimental Medicine- Biochemistry section, University of Genoa, Viale Benedetto XV, 1, 16132 Genoa, Italy

关键词: Calpastatin;    Calpain regulation;    Protein kinase C;    Rat brain;    PKC;    protein kinase C;    PKA;    protein kinase A;    EDTA;    ethylene diamine tetraacetate;    GST;    glutathion S-transferase;   

DOI  :  10.1016/S0014-5793(99)00461-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

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 Ca²⁺ 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.

【 授权许可】

Unknown