A sperm motility inhibitor of seminal plasma.

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The seminal plasma motility inhibitor (SPMI) has recently been purified from boar seminal plasma where its molecular weight has estimated at 50,000 by molecular sieving but three peptides of 14k, 16k, 18k were detected after SDSPAGE in denaturing conditions. We succeeded the cloning of boar 14k SPMI cDNA gene. Nucreotide sequence analysis of the 645-base pair SPMI cDNA predicts a code peptide of 137 amino acid residues which includes a 21residue signal peptide and a 116-residue secreted protein.The levels of SPMI gene expression were determined by Northrn blot analysis using the probe DNAe encoding the open reading frame of the cloned SPMI cDNA gene. It was soon noticed that the boar seminal vesicle is extrordinarily abundant in SPMI mRNA (after 3 hrs expousure). In contrast, there was no detectable level of SPMI expression in the testis, epididymis, prostate, bulbourethral gland, urinary bladder, liver, spleen, as well as in the reproductive organs of the sow and also human seminal vesicles. Thus it would appear that the expression of the SPMI gene is highly specific to the seminal vesiclesWe succeeded the expression of protein from the cloned SMPI cDNA gene.Expressed protein reacted against SPMI antibody by western blotting. Although this expressed SPMI protein was able to solubilize with some buffers, SPMI biological activity was lost. Further studies needs to resolve this problem.The causes of asthenozoospermia (patient with poor motile sperm) were still not clear. We already observed that the inhibitory capacity of seminal plasma from patients with poor sperm motility was not significantly different from that of seminal plasma from normal fertile men with good sperm motility. Now we are studying whether a motility inhibitor within poor motile spermatozoa present and is identical to SPMI.But, presently, we can not show