Intra Acrosomal Protein Products

Intra Acrosomal Protein is a testis-specific, differentiation antigen, acrosomal vesicle protein 1, that arises within the acrosomal vesicle during spermatogenesis, and is associated with the acrosomal membranes and matrix of mature sperm. The gene encoding this protein consists of 4 exons and its alternative splicing generates 11 distinct transcripts, which encode protein isoforms ranging from 81 to 265 amino acids. The longest transcript is the most abundant, comprising 53-72% of the total acrosomal vesicle protein 1 messages; the second largest transcript comprises 15-32%; the third and the fourth largest transcripts account for 3.4-8.3% and 8.7-12.5%, respectively; and the remaining 7 transcripts combined account for < 1% of the total acrosomal vesicle protein 1 message. It is suggested that phenomena of cryptic splicing and exon skipping occur within this gene. The acrosomal vesicle protein 1 may be involved in sperm-zona binding or penetration, and it is a potential contraceptive vaccine immunogen for humans.