Submitted to: DNA and Cell Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 28, 1994
Publication Date: N/A
Interpretive Summary: The process of fertilization in mammals encompasses a sperm cell-egg interaction which involves biochemically related events. In this study the molecular cloning and the sequence analysis of the cDNA encoding for boar acrosin inhibitor was investigated. This enzyme is secreted at ejaculation from the seminal vesicles into the semen where it binds to a group of proteins called spermadhesins. Its function are speculated to be to neutralize acrosin released by damaged sperm, thus acting to protect normal sperm cells and the lining of the reproductive tract during sperm transit and to protect the membrane surrounding the egg , the zona pellucida. It had been previously reported that several forms of this enzyme are present in different tissues and reproductive fluids. This study demonstrated that only one form of the enzyme is present and that the other forms are most likely degradation products. This demonstrated that there is a only one copy of the acrosin inhibitor gene in the pig genome.
A full-length cDNA encoding the porcine acrosin inhibitor has been isolated from a boar seminal vesicle cDNA library. Nucleotide sequence analysis of the 667-bp cDNA predicts a precursor protein of 97 amino acid residues, which includes a 26-residue signal peptide and a 71-residue secreted protein. The predicted amino acid sequence of the mature protein agrees completely with that of the sperm-associated acrosin inhibitor determined by conventional amino acid sequence analysis. However, the asparagine/aspartic acid and glutamine/glutamic acid substitutions, as reported in the seminal plasma counterpart, have not been observed. Southern blot analysis shows only a single hybridizing band with three different restriction endonucleases, suggesting the presence of a singe copy of the acrosin inhibitor gene in the porcine genome.