Crawford C, Brown N R, Willis A C
Department of Zoology, University of Oxford, U.K.
Biochem J. 1990 Jan 15;265(2):575-9. doi: 10.1042/bj2650575.
Two forms of pig kidney calpain II were isolated, both of which appeared to contain an intact 80 kDa large subunit, but which showed specific proteolytic degradation at the N-terminal end of the 30 kDa small subunit. The structure of each of these molecules was investigated by amino acid sequence analysis. The forms corresponded to molecules with small subunits starting at residue 38 (degraded calpain A) and at residue 62 (degraded calpain B) of the complete sequence. These molecules were tested for their ability to interact with phosphatidylinositol and with carbohydrate (agarose gel-filtration media). Calpain and degraded calpain A, but not degraded calpain B, would interact with phosphatidylinositol. Thus the sequence (G)17TAMRILG (residues 38-61) is essential for the interaction. Neither calpain nor the degraded forms of the enzyme showed specific interaction with carbohydrate.
分离出了两种形式的猪肾钙蛋白酶II，它们似乎都含有完整的80 kDa大亚基，但在30 kDa小亚基的N端显示出特异性的蛋白水解降解。通过氨基酸序列分析研究了这些分子中每一个的结构。这些形式对应于小亚基从完整序列的第38位残基（降解钙蛋白酶A）和第62位残基（降解钙蛋白酶B）开始的分子。测试了这些分子与磷脂酰肌醇和碳水化合物（琼脂糖凝胶过滤介质）相互作用的能力。钙蛋白酶和降解钙蛋白酶A能与磷脂酰肌醇相互作用，但降解钙蛋白酶B不能。因此，序列(G)17TAMRILG（第38 - 61位残基）对于这种相互作用至关重要。钙蛋白酶及其降解形式均未显示出与碳水化合物的特异性相互作用。
