Hansson V, Ritzen M E, French F S, Weddington S C, Nayfeh S N
Mol Cell Endocrinol. 1975 Jul;3(1):1-20. doi: 10.1016/0303-7207(75)90028-3.
Testicular androgen-binding proteins (ABP) in rabbit testis, caput epididymis and efferent duct fluid (EDF) were compared to a similar androgen-binding protein TeBg) in rabbit serum. The affinity of these proteins for 5alpha-dihydrotesterone (DHT) at 0 degrees C (KaABP = 1.6 X 10(9) M-1 and KaTeBG = 1.9 X 10(9) M-1) and their steroid specificities were similar (DHT greater than androstanediol greater than progesterone and androstenedione). ABP and TeBG had also almost identical Stokes radii (42.8 +/- 1.2 and 43.9 +- 0.8 A, respectively), sedimentation coefficients (4.7 +/- 0.2 S and 4.4 +/- 0.2 S, respectively) and electrophoretic mobility (Rf = 0.4 in 6 1/2% polyacrylamide gels). Calculation of molecular weights from Stokes radii and sedimentation rates indicated a molecular weight of 74,000 (69,000-78,000) for TeBG and 76,000 (71,000-82,000) for ABP. The corresponding frictional ratios were 1.61 for TeBG and 1.55 for ABP assuming a partial specific volume (v) of 0.70 cm3/g. Polyacrylamide gel electrophoresis (PAGE) at different gel concentrations gave a mean molecular radius of 2.74 nm, also indicating a molecular weight of about 75,000 (v = 0.70 cm3/g. ABP and TeBG could not be separated by PAGE; however, partial separation of ABP and TeBG was achieved by isoelectric focusing and ion-exchange chromatography on DEAE-cellulose. TeBG focused at pH 5.4, whereas ABP formed a distinct peak of bound radioactivity at pH 4.7. Also by ionexchange chromatography, ABP in both testis and epididymal supernatants was shown to have an apparently higher surface charge than TeBG in rabbit serum. The concentration of ABP in efferent duct fluid (2 X 10(-7) M = 60 pmol/mg protien) was much higher than TeBG in male rabbit serum (5.2 X 10(-8) M = 0.7 pmol/mg protein). These findings ruled against the possibility that ABP in the testis and epididymis could have been derived directly from serum. It is concluded that ABP and TeBG are very similar if not identical proteins both serving as transport and carrier proteins in their respective compartments.
将兔睾丸、附睾头和输出小管液（EDF）中的睾丸雄激素结合蛋白（ABP）与兔血清中一种类似的雄激素结合蛋白（TeBg）进行了比较。这些蛋白在0℃时对5α-二氢睾酮（DHT）的亲和力（KaABP = 1.6×10⁹ M⁻¹，KaTeBG = 1.9×10⁹ M⁻¹）及其类固醇特异性相似（DHT＞雄烷二醇＞孕酮和雄烯二酮）。ABP和TeBG的斯托克斯半径也几乎相同（分别为42.8±1.2 Å和43.9±0.8 Å），沉降系数（分别为4.7±0.2 S和4.4±0.2 S）和电泳迁移率（在6.5%聚丙烯酰胺凝胶中Rf = 0.4）。根据斯托克斯半径和沉降速率计算分子量，表明TeBG的分子量为74,000（69,000 - 78,000），ABP的分子量为76,000（71,000 - 82,000）。假设偏比容（v）为0.70 cm³/g，TeBG和ABP相应的摩擦比分别为1.61和1.55。在不同凝胶浓度下进行聚丙烯酰胺凝胶电泳（PAGE）得到的平均分子半径为2.74 nm，也表明分子量约为75,000（v = 0.70 cm³/g）。ABP和TeBG不能通过PAGE分离；然而，通过等电聚焦和在DEAE - 纤维素上的离子交换色谱法实现了ABP和TeBG的部分分离。TeBG在pH 5.4聚焦，而ABP在pH 4.7形成一个明显的结合放射性峰。同样通过离子交换色谱法，睾丸和附睾上清液中的ABP显示出比兔血清中的TeBG具有明显更高的表面电荷。输出小管液中ABP的浓度（2×10⁻⁷ M = 60 pmol/mg蛋白质）远高于雄性兔血清中TeBG的浓度（5.2×10⁻⁸ M = 0.7 pmol/mg蛋白质）。这些发现排除了睾丸和附睾中的ABP可能直接来源于血清的可能性。结论是ABP和TeBG是非常相似的蛋白，即使不完全相同，它们在各自的区域中都作为转运和载体蛋白发挥作用。
