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A protein in rat ventral prostate cytosol that -binds estramustine [estradiol 3-bis(2-chloroethyl)carbamate] was purified to homogeneity by using chromatography on DEAEcellulose, Sephadex G-100 (superfine), octyl-Sepharose CL4B, and polyacrylamide gel electrophoresis. The [3H]estramustine, the drug is initially accumulated in the prostatic epithelium and subsequently secreted into the lumina of the prostatic lobuli (5). These findings might indicate that estramustine binds to a protein in the prostate cell and that the estramustine-protein complex is secreted into the prostatic fluid.To study this specific protein and the mechanism of action of estramustine further, the estramustine-binding protein has been purified from rat ventral prostate. Antibodies have been raised against this protein and its distribution in male and female rats has been studied by using radioimmunoassay. All of the following purification procedures were performed at 0-4°C unless stated otherwise. DEAE-Cellulose Chromatography. A column (1.5 X 22 cm) of DEAE-cellulose (Whatman DE-52) was prepared and equilibrated with TEKG buffer containing 0.25 mM dithiothreitol (TEKGD buffer). After application of sample to the column, elution was with 60 ml of TEKGD buffer and a 2 X 150 ml 0.01-0.30 M KCl linear gradient in TEKGD buffer. The flow rate was adjusted to 1 ml/min and absorbance was measured continuously '4 280 nm. Fractions (2 ml) were collected and analyzed for radioactivity and conductivity. Fractions containing radioactivity were pooled and concentrated to 4 ml in a collodion bag (Sartorius membrane filter).Gel Filtration on Sephadex G-100. Sephadex G-100 (superfine; Pharmacia) was packed in a 2.5 X 50 cm column. The column was equilibrated with TEKGD buffer and calibrated with eight proteins with known molecular weights ranging from 13,700 to 151,000. The concentrate from the DEAE-cellulose step was applied to the column and chromatography was carried out at a flow rate of 5 ml/hr. Fractions (2 ml) were collected and examined for radioactivity. Fractions containing radioactivity were pooled and a saturated ammonium sulfate solution (in TEKGD buffer at 0WC, pH 7.4) was added to give a final ammonium sulfate concentration of 20% saturation.Octyl-Sepharose Chromatography. A gel bed of 7-8-ml of octyl Sepharose CL-4B (Pharmacia) was layered on top of 1 ml of Sephadex G-25 (medium) in a 0.9 X 30 cm column. The Abbreviation: NaDodSO4, sodium dodecyl sulfate. 3149The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U. S. C. §1734 solely to indicate this fact.

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Högberg, B. and B. Uvnas. Further observations on the disruption of rat mesentery mast cells caused by compound 48/80, antigen‐antibody reaction, lecithinase A, and decylamine. The influence of pH, ionic milieu, temperature and enzyme inhibitors, on the disrupting action on rat mesentery mast cells of compound 48/80, antigen and decylamine has been investigated. A pH optimum around 7.4, the essentiality of Ca++ ions, the influence of temperature and the inhibitory action of various enzyme inhibitors, especially those blocking protein NH2‐groups and SH‐groups, supported the view that compound 48/80 and antigen disrupt the mast cells by activating a lytic enzyme attached to the mast cell membrane. Decylamine, on the other hand, is a surface active agent that disrupts mast cells by a non‐enzymatic mechanism.