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Of three kinds of commercial zwitterionic detergents [SB 12, SB 14, and 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (Chaps)], SB 12 and Chaps were more useful than SB 14 because of high solubility and less interference with protein assay. Efficiency for protein solubilization at pH 6-9 was higher for SB 12 than for Chaps with either calf thymus chromatin or rat liver nuclei. At pH 9 and ionic strength (I) = 0.35, 1% SB 12 and 1% Chaps were capable of solubilizing about 70% and about 47% of total proteins in rat liver nuclei, respectively. Core histones in rat liver nuclei were extracted to a lesser extent with Chaps than with SB 12. DNA-dependent RNA polymerase and isopeptidase activities were barely inactivated by 1% Chaps at pH 8-9, but isopeptidase activity was inhibited by 0.3% SB 12. These facts indicate that whereas SB 12 is effective for solubilization of whole nuclear proteins, Chaps is suitable for the selective extraction of nonhistone chromosomal proteins without denaturation.

Age-related changes of chromosomal proteins in the dorsolateral and ventral prostates of rats from 6 to 31 weeks of age were studied by SDS-polyacrylamide gel electrophoresis. A nonhistone protein having a molecular weight of about 20,000 (20K-NHP), abundantly localized in the dorsolateral prostate, increased rapidly in content during the early stage of sexual maturation (6-11 weeks of age) in association with increases of serum testosterone concentration and prostatic tissue weight. Serum testosterone concentration decreased after week 11 and then remained constant until week 31. In contrast, the 20K-NHP content continued to increase after 11 weeks of age in the dorsolateral prostate, but not in the ventral prostate. The rapid increase of 20K-NHP in the dorsolateral prostate during the early stage of sexual maturation could not be attained in immature rats (5 weeks of age) by injection of excess amounts of androgens and/or prolactin for a week. But the 20K-NHP content in the ventral prostate of rats treated with testosterone propionate was almost the same as that of mature rats.

Distribution of an androgen-dependent, 20,000-dalton nonhistone protein with a pI of about 11.5 (20K-NHP) was examined by electrophoretic techniques. Nuclei of the brain, liver, spleen, skeletal muscle, lung, and thymus of rats contained a negligible amount of 20K-NHP, whereas 20K-NHP was distinctly detectable, in different relative amounts, in the nuclei of the male accessory sex organs, with the dorsolateral prostate having the highest relative content (100%), followed by the coagulating gland (approximately equal to 16%), the ventral prostate (approximately equal to 6%), and the seminal vesicle (approximately equal to 2%). There were heterogeneous distributions of cytosol components, acid phosphatase isozymes, and nonhistone proteins in the dorsolateral prostate. Zinc was localized in the lateral lobe, and fructose and glucose were in the dorsal lobe. Cytosol proteins with pI 7.5, 8.2, and 8.5 were abundant in the dorsal lobe, and proteins with pI 7.4 and 8.0 in the lateral lobe. Acid phosphatase isozymes with pI 7.1, 7.4, 7.7, and 8.0 were abundantly distributed in the lateral lobe. Of the nonhistone proteins, 20K-NHP showed the highest content both in the lateral lobe and in the dorsal lobe. It was found that 20K-NHP was more abundantly distributed in the lateral lobe (maximally four times higher) than in the dorsal lobe. The heterogeneous distribution of 20K-NHP in the dorsolateral prostate was strikingly similar to that of zinc. It appears, therefore, that 20K-NHP is closely related to dorsolateral prostate zinc content.

Nuclei of the dorsolateral prostate of rats contain a large amount of androgen-dependent non-histone protein (20K-NHP) (mol. wt. not equal to 20,000; pI not equal to 11.5) (Matuo et al. (1]. Its content in the nuclei increased most markedly during 4-8 weeks of age, when functional differentiation of the prostate was most active on the basis of the changes of major cytosol proteins and zinc. Nuclei of the Dunning tumors originating in the dorsolateral prostate were found to lack 20K-NHP regardless of androgen dependency, indicating the disappearance of the 20K-NHP from the nuclei by dedifferentiation. These suggest that the 20K-NHP is an important nuclear protein for differentiation of the dorsolateral prostate cells.

Proteins in the cytosol, postnuclear particulate, and nuclear fractions from seven specimens of normal prostate from bladder cancer patients, 14 specimens of benign hypertrophic prostate (BPH), and three specimens of cancerous prostate were analyzed and compared by SDS-polyacrylamide slab gel electrophoresis. Abundant protein species in the cytosol fractions were 60K (species having a molecular weight of about 60,000) and 42K; their relative contents were about 35% for 60K and about 12% for 42K. In the postnuclear particulate fraction, 42K was the most abundant (about 10% of the total). The contents of these major protein species were similar in specimens of normal and diseased prostates. In addition, there are marked similarities in the electrophoretic patterns for all the protein (24-29 species) in the cytosol and postnuclear particulate fractions of the human prostate, except for four minor species in the cytosol fraction. Of the nuclear proteins, the content of core histones (H2A, H2B, H3, and H4) was fundamentally similar among all the specimens, whereas the content of H1 histone was different from one specimen to another. The most remarkable and significant difference was that the 42K-NHP (nonhistone protein having a molecular weight of about 42,000), 55K-NHP, and 190K-NHP concentrations were significantly higher in BPH than in normal and cancerous prostates.