|Kwok Simon C M|
Submitted to: Molecular Biology in Medicine Bulletin
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/28/1993
Publication Date: N/A
Citation: Interpretive Summary: During ejaculation sperm cells are mixed with male accessory sex organ secretions and are coated on the cell surface with proteins. These sperm coating proteins were the subject of this study. The biological significance of these so-called spermadhesin proteins is unknown but is thought to be involved in sperm-egg recognition, protectors of the sperm cell during transit in the female reproductive tract, regulators of sperm cell maturation, and protect the sperm cell from immunosuppressive factors in the female reproductive tract. In this study two major proteins were identified in boar semen and were designated PSP-I and PSP-II. The cDNA nucleotide sequence which encodes these proteins was determined. Based on their sequence and structural similarities with spermadhesins and their site of synthesis in the male reproductive tract, it is concluded that these proteins are new members of the spermadhesin family. The knowledge gained in this study provides new information on the factors involved in the storage of domestic animal semen as well as gaining insight into the process of mammalian fertilization.
Technical Abstract: A full-length cDNA encoding 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/glutamine acid substitutions as reported in the seminal plasma counterpart has not been observed. Southern blot analysis shows only a single hybridizing band with three different restriction endonucleases, suggesting the presence of a single copy of the acrosin inhibitor gene in the porcine genome. The sequence discrepancy between the sperm-associated acrosin inhibitor and its seminal plasma counterpart may be due to allelic difference.