Androgen-sensitive spermine-binding protein of rat ventral prostate. Purification of the protein and characterization of the hormonal effect

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Abstract
The rat ventral prostate contains a cytosol protein that can non-covalently bind spermine much more tightly than spermidine or other natural diamines. The protein was purified to homogeneity, as judged by electrophoresis in urea- and sodium dodecyl sulfate-containing polyacrylamide gels. The protein, with or without spermine bound to it, sediments at 3S in a sucrose gradient with or without 0.4 M KCl. The MW of the protein is about 30,000. Each molecule of the binding protein can bind 1 molecule of spermine. In the prostate of rats injected with cycloheximide, the protein appears to have a half-life of about 3.5 h. The spermine-binding activity of an acidic fraction obtained by DEAE-cellulose chromatography of the prostate cytosol proteins is reduced by about 40-60% within 20-40 h after castration. This effect is reversed very rapidly within 15-30 min by i.p. injection of 5 .alpha.-dihydrotesterone. The hormonal effect is androgen-specific and is not mimicked by dexamethasone or estradiol-17.beta.. The androgen effect was reduced significantly when rats were injected with cycloheximide or actinomycin D, suggesting that the acidic protein may be one of the earliest proteins induced by androgen in the rat ventral prostate.