Purification of major abundance class of poly(A+)-RNA from rat ventral prostate

Influence of castration and androgen treatment on the synthesis of prostatic binding protein and the concentration of its mRNA in the rat ventral prostate

The regulation by androgens of the synthesis of prostatic binding protein (PBP), an abundant secretory protein of the rat ventral prostate, was studied by measuring the rate of incorporation of [3H]leucine into total protein and into PBP by prostatic tissue in vitro. PBP-specific synthesis dropped to 30% of the intact level after 3 days and to 5.5% after 7 days. Administration of androgens to 7 day-castrated rats reversed these changes: 36% of the control value was reached after 3 days of treatment and 70% after 5 days. The mRNAs of PBP were measured under similar conditions by means of dot hybridization, using C1-, C2- and C3-specific cDNA-clones. The 3 mRNAs followed a parallel course. They decreased to about 18% on the third day after castration and to about 2% after 7 days. Androgen treatment of 7-day castrated rats produced a small increase of these levels after 1 day. After 3 days 15% of the intact level was reached. The general similarity of the time course of PBP synthesis and PBP mRNA levels in castrated and androgen treated rats supports a transcriptional regulation mechanism, although there also is some evidence for an influence on protein synthesis in general.

In vitro translation of major abundant class poly(A+)-mRNA from rat seminal vesicle

Total poly (A)-containing messenger RNA [poly(A)-mRNAT] was isolated from seminal vesicles of adult male rats. By preparative 5%-20% linear sucrose gradient centrifugation in 1% SDS, a single peak was seen in the 11S region [poly(A)-mRNA11S]. Poly (A)-mRNAT and poly(A)-mRNA11S were translated in the wheat germ S-30 in vitro translation system. Laemmli-SDS-polyacrylamide slab gel electrophoresis of translation products of poly(A)-mRNAT revealed three major protein bands at approximately 18,500, 15,000, and 14,000 daltons. In vitro translation of poly(A)-mRNA11S across the 11S peak revealed partial purification of the mRNAs for the three predominant proteins. The lower molecular weight part of the 11S peak enriched for the mRNAs coding for the 15,000 and 14,000 dalton polypeptides, and the higher molecular weight side of the peak enriched for the 18,500 dalton mRNA. The highly abundant class of mRNA from rat seminal vesicle can be purified with one sucrose gradient centrifugation.