Existence of protease inhibitors (PIs) in the sexual glands of mammals is well known. They have physiological functions in addition to their inhibitory effect on protease activity. It is believed that they are important for the protection of genital tract epithelium against proteolytic damage and/or have a regulatory role in the fertilization process. The trypsin-like activity seems to involve the binding of mouse spermatozoa to the zona pel-lucida. In rat seminal vesicle, one calcium transport inhibitor (caltrin), which is identical to pancreatic secretory trypsin inhibitor, is able to suppress Ca2+ uptake by spermatozoa to prevent a premature acrosome reaction far from the oviduct. Hence, the study of PIs in the genital tract becomes an important subject of reproductive biology.
We have purified a PI of M 6126 from mouse seminal vesicle secretions (SVS) and identified it as a Kazal-type trypsin inhibitor with very strong affinity to trypsin.
It is a basic polypeptide of 57 amino acid residues with no glycoconjugate. Its primary structure is identical to P12 deduced from P12 cDNA that has been cloned from mouse ventral prostate by Mills et al.. Recently, a recombinant P12 with full activity of the naturally occurring P12 was recovered from a chimerical polypeptide of glutathi-one-S-transferase and P12 (GST-P12) expressed in Escherichia coli. antibiotics levaquin
The P12 RNA message is detectable in the male accessory sexual glands of adult mice while its expression is constitutive in pancreas. Substantial progress has been made to establish its genomic structure. As a result, the DNA-binding sites for some transcription factors such as GC2 and SP1 have been identified in this gene. On the other hand, less progress has been made in studying the role of P12 in reproductive biology despite its presence in SVS. Accordingly, we conducted this work to better understand the characteristics of P12-sperm binding as well as the developmental profiles of P12 in the seminal vesicle and its binding sites during sperm generation in the testis. In addition, we assessed the ability of P12 to suppress Ca2+ uptake by spermatozoa.