Identification of androgen-induced proteins in human epididymis

Androgenic stimulation (0.1 microM testosterone or 5 alpha-dihydrotestosterone in the medium) of cultured human epididymal tubules increased the synthesis of five proteins, identified by their mobility relative to albumin (Ra) in polyacrylamide gels as 0.31, 0.43, 0.67, 0.81 and 1.01. This effect was inhibited by the simultaneous presence of 10 microM cyproterone acetate in the medium. The caput epididymidis was the most active region in the production of these proteins and a gradient of decreasing activity was found in successive segments. The appearance of induced proteins in the culture medium suggests their secretory nature, while some data indicate that androgens may also affect the secretory process. Bands corresponding to Ra 0.31, 0.43, 0.68 and 1.01 were found in caput and cauda epididymidis fluids, while bands coincident with Ra 0.31 and 0.43 were consistently found in extracts (0.5 M NaCl) of caudal spermatozoa. Preliminary determinations of molecular weight and isoelectric point for the different bands yielded the following results: Ra 0.31, 38,000 and 5.8; Ra 0.43, 21,000 and 6.2; Ra 0.68, 69,000 and 5.1; Ra 0.81, 13,900 and 6.8; and Ra 1.01, 29,000 and 6.8.