REGULATION OF THE EPIDIDYMAL SYNTHESIS OF P26H, A HAMSTER SPERM PROTEIN

We have previously identified a 26-kDa epididymal hamster sperm glycop rotein (P26h) that is involved in gamete interaction. This protein is added to the acrosomal cap during epididymal transit of spermatozoa. B ecause the epididymis secretes proteins under androgen control, the ai m of this study was to document the testicular control of the epididym al ontogenesis of P26h. The cytosolic fraction of the epididymides of male hamsters of different ages, prepared by ultracentrifugation, was used as well as those from mature males at different times following c astration. These extracts were Western blotted and probed with an anti -P26h antiserum. P26h was initially immunodetectable in extracts prepa red from hamsters 4 weeks of age, and the signal increased up to the 7 th week of age. The P26h signal decreased rapidly after castration unt il the antigen was undetectable at 3 days following castration. Admini stration of testosterone to 3-week-old male hamsters resulted in the e pididymal expression of P26h earlier than that observed in untreated o r control animals. These results suggest that P26h protein expression in hamster epididymis is under testicular androgen control.