Bordin S, Petra P H
Proc Natl Acad Sci U S A. 1980 Oct;77(10):5678-82. doi: 10.1073/pnas.77.10.5678.
The sex steroid-binding protein (SBP) present in the serum of the monkey Macaca nemestrina is shown to exist in cells of tissue involved in reproduction. The localization was demonstrated by immunofluorescence with monospecific antibodies raised against homogeneous human SBP. These antibodies were previously shown to crossreact with monkey SBP. The protein appears to be located in the cytoplasm of epithelial cells lining the prostate alveoli, the ducti of the epididymis, and the seminiferous tubula of the testes of the monkey. The protein is also present in the cytoplasm of parenchymal cells of the liver, where SBP is believed to be synthesized, and in cells of the adrenal cortex, where steroids are known to be synthesized. Controls appear dark and illustrate specificity of the immunofluorescence, ruling out both tissue autofluorescence and other nonspecific interactions. In all cases, the relative intensity of fluorescence appears minimal in the nuclei of cells. Experiments performed with cultured MCF-7 cells indicate that SBP can across the plasma membrane and enter into the cytoplasm but not into the nucleus. Additional studies indicate that the monospecific antibodies do not crossreact with the monkey prostate androgen receptor, as shown by ultracentrifugation in sucrose densty gradients. The physiological significance of these observations is not known; however, the existence of this protein in cells of target tissues for sex steroids introduces a new dimension in our thinking about the role of this protein in androgen action.
猕猴血清中的性类固醇结合蛋白（SBP）被证明存在于参与生殖的组织细胞中。通过用针对纯合人SBP产生的单特异性抗体进行免疫荧光法来证明其定位。这些抗体先前已被证明可与猴SBP发生交叉反应。该蛋白似乎位于猕猴前列腺腺泡内衬上皮细胞、附睾管以及睾丸生精小管的细胞质中。该蛋白也存在于肝脏实质细胞的细胞质中（据信SBP在此合成）以及肾上腺皮质细胞中（已知类固醇在此合成）。对照呈现深色，说明了免疫荧光的特异性，排除了组织自发荧光和其他非特异性相互作用。在所有情况下，细胞细胞核中的荧光相对强度似乎最小。用培养的MCF - 7细胞进行的实验表明，SBP可以穿过质膜进入细胞质，但不能进入细胞核。另外的研究表明，如在蔗糖密度梯度中超离心所示，单特异性抗体不会与猴前列腺雄激素受体发生交叉反应。这些观察结果的生理意义尚不清楚；然而，这种蛋白在性类固醇靶组织细胞中的存在为我们思考该蛋白在雄激素作用中的角色引入了一个新的层面。
