Baba T, Michikawa Y, Kashiwabara S, Arai Y
Institute of Applied Biochemistry, University of Tsukuba, Ibaraki, Japan.
Biochem Biophys Res Commun. 1989 May 15;160(3):1026-32. doi: 10.1016/s0006-291x(89)80105-6.
A 32-kDa protein was purified from acrosomal extracts of ejaculated boar spermatozoa as a complex with 55- and 53-kDa proacrosins. In the presence of the 32-kDa protein, these proacrosins were sequentially converted by autoactivation to a 49-kDa intermediate, a 43-kDa intermediate, and then a 35-kDa mature acrosin. This activation process was consistent with that in the absence of the 32-kDa protein, but differed in producing the 49-kDa form as the predominant acrosin intermediate. Thus, the 32-kDa protein may be a regulatory protein for proacrosin activation. The 49-kDa intermediate was a two-chain polypeptide with the amino-terminal sequences corresponding to those of the light and heavy chains of mature acrosin, whereas the carboxyl-terminal sequence of its heavy chain was identical with that of the 53-kDa proacrosin. These results suggest that the 49-kDa intermediate is produced from 53-kDa proacrosin during proacrosin activation by the cleavage of the peptide bond between Arg-23 and Val-24, which results in the formation of the light and heavy chains.
从射精的公猪精子顶体提取物中纯化出一种32 kDa的蛋白质，它与55 kDa和53 kDa的前顶体蛋白酶形成复合物。在32 kDa蛋白质存在的情况下，这些前顶体蛋白酶通过自身激活依次转化为49 kDa中间体、43 kDa中间体，然后是35 kDa的成熟顶体蛋白酶。这种激活过程与不存在32 kDa蛋白质时一致，但不同之处在于产生的49 kDa形式是主要的顶体蛋白酶中间体。因此，32 kDa蛋白质可能是前顶体蛋白酶激活的调节蛋白。49 kDa中间体是一种双链多肽，其氨基末端序列与成熟顶体蛋白酶轻链和重链的序列相对应，而其重链的羧基末端序列与53 kDa前顶体蛋白酶的相同。这些结果表明，49 kDa中间体是在顶体蛋白酶激活过程中由53 kDa前顶体蛋白酶通过切割Arg-23和Val-24之间的肽键产生的，这导致了轻链和重链的形成。
