Rat sperm acrosin: cDNA sequence, derived primary structure and phylogenetic origin

Rat preproacrosin primary structure as predicted from a 1431 nucleotide (nt) cDNA indicates that the molecule is synthesized as a preproenzym consisting of a putative 19 amino acid signal sequence, a 23 amino acid light chain and finally a 395 amino acid heavy chain. Functional domains like the catalytic triad (His-70, Asp-124, Ser-222) are highly conserved not only between the available acrosin primary structures of different mammals but also in comparison with other serine proteinases. Number of amino acid exchanges and the degree in amino acid identity between the different serine proteinases and rat acrosin leads to the assumption that acrosin is one of the early descendants within the phylogenetic tree of the serine proteinase superfamily.