Proacrosin activation in the presence of a 32-kDa protein from boar spermatozoa.
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.
Baba
T
T
Institute of Applied Biochemistry, University of Tsukuba, Ibaraki, Japan.
Michikawa
Y
Y
Kashiwabara
S
S
Arai
Y
Y
D000176:Acrosin / Q000032:analysis / Q000378:metabolism*; D000177:Acrosome / Q000032:analysis*; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation / Q000187:drug effects; D004792:Enzyme Precursors / Q000032:analysis / Q000378:metabolism*; D008297:Male; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments / Q000378:metabolism; D011506:Proteins / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*; D012697:Serine Endopeptidases / Q000378:metabolism*; D013094:Spermatozoa / Q000032:analysis*; D013552:Swine
D000596:Amino Acids; D004792:Enzyme Precursors; D010446:Peptide Fragments; D011506:Proteins; D012697:Serine Endopeptidases; C022438:proacrosin; D000176:Acrosin