Modulation of calpastatin specificity in rat tissues by reversible phosphorylation and dephosphorylation - PubMed (original) (raw)

Comparative Study

. 1994 Mar 30;199(3):1326-32.

doi: 10.1006/bbrc.1994.1376.

Affiliations

Comparative Study

Modulation of calpastatin specificity in rat tissues by reversible phosphorylation and dephosphorylation

F Salamino et al. Biochem Biophys Res Commun. 1994.

Abstract

Two calpastatins, with Mr 110 KD and named calpastatin I and II, have been isolated from rat heart and kidney and displayed distinct inhibitory efficiency with mu- and m-calpain, respectively, as those isolated from rat skeletal muscle. Whereas the level of calpastatin I always exceeds that of mu-calpain, the level of calpastatin II appears to be more closely correlated to the level of m-calpain. As previously shown for skeletal muscle, the two inhibitor proteins can be interconverted by a phosphorylation-dephosphorylation reaction; the enzyme responsible for phosphate incorporation in calpastatin I is now identified in c-AMP dependent protein kinase A. In rat erythrocytes, containing a single calpain form, the single low Mr calpastatin form does not undergo reversible phosphorylation and is equally efficient in respect to typical mu- and m-calpain. The presence of two interconvertible calpastatin forms provides the cells with a highly sensitive mechanism of regulation of the Ca(2+)-dependent proteolytic system.

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