Melloni E, Michetti M, Salamino F, Sparatore B, Pontremoli S
Institute of Biological Chemistry, University of Genoa, Italy.
Biochem Biophys Res Commun. 1998 Aug 28;249(3):583-8. doi: 10.1006/bbrc.1998.9200.
Rat brain contains a calpain activator specific for the mu-form of the proteinase. We now report that this protein factor binds to the catalytic 80 kDa calpain subunit, promoting the dissociation of the heterodimer structure of the proteinase. The successive steps of the activation process, namely the two autoproteolytic steps producing the 78 kDa and the 75 kDa calpain forms, result in a 100 times faster rate. The activator competes with calpastatin and associates with the inner surface of plasma membranes. Based on its properties, the calpain activator can be visualised as the molecule indicating the sites for calpain activation at which the proteinase can also elude the negative control exerted by calpastatin.
大鼠脑含有一种对蛋白酶μ型具有特异性的钙蛋白酶激活剂。我们现在报告，这种蛋白质因子与催化性80 kDa钙蛋白酶亚基结合，促进蛋白酶异二聚体结构的解离。激活过程的连续步骤，即产生78 kDa和75 kDa钙蛋白酶形式的两个自蛋白水解步骤，导致反应速率加快100倍。该激活剂与钙蛋白酶抑制蛋白竞争，并与质膜内表面结合。基于其特性，钙蛋白酶激活剂可被视为指示钙蛋白酶激活位点的分子，在这些位点蛋白酶也可以避开钙蛋白酶抑制蛋白施加的负调控。
