Ranke M B, Stanley C A, Rodbard D, Baker L, Bongiovanni A, Parks J S
Proc Natl Acad Sci U S A. 1976 Mar;73(3):847-51. doi: 10.1073/pnas.73.3.847.
Since liver is a target for growth hormone action, binding of 125I-labeled human growth hormone to enzymatically isolated rat hepatocytes was studied. Specific binding was shown with hepatocytes from both male and female animals. There was a single class of receptors for human growth hormone on cells from males (affinity constant, Ka = 1.16 x 10(9) liters/mole; sites per cell, q = 6200). In males, bovine growth hormone was almost as potent as human growth hormone in displacing bound 125I-labeled human growth hormone, while ovine prolactin was about 1000 times less potent. Cells from female rats bound more 125I-labeled human growth hormone than cells from males. The cells from females contained at least two classes of receptors for human growth hormone. The receptor of highest affinity had the same affinity for human growth hormone as the single receptor found in males (Ka = 0.96 x 10(9) liters/mole). However, there were three to four times as many of these receptors per cell in females (q = 21,000). In females, bovine growth hormone and ovine prolactin were both about 20 times less potent than human growth hormone. Treatment of male rats with estrone produced cells that show the same binding characteristics as females. These results indicate that human growth hormone binds to a somatogenic receptor in hepatocytes from male rats. In females and estrogen-treated males, the receptors that bind human growth hormone recognize lactogenic as well as somatogenic properties. This suggests that the lactogenic and growth-promoting effects of human growth hormone in the rat are mediated by different receptors.
由于肝脏是生长激素作用的靶器官，因此研究了125I标记的人生长激素与酶分离的大鼠肝细胞的结合情况。雄性和雌性动物的肝细胞均显示出特异性结合。雄性动物细胞上存在一类人生长激素受体（亲和常数，Ka = 1.16×10⁹升/摩尔；每个细胞的结合位点，q = 6200）。在雄性动物中，牛生长激素在置换结合的125I标记人生长激素方面几乎与人生长激素一样有效，而绵羊催乳素的效力约低1000倍。雌性大鼠的细胞比雄性大鼠的细胞结合更多的125I标记人生长激素。雌性大鼠的细胞至少含有两类人生长激素受体。亲和力最高的受体对人生长激素的亲和力与在雄性动物中发现的单一受体相同（Ka = 0.96×10⁹升/摩尔）。然而，雌性大鼠每个细胞中的这类受体数量是雄性大鼠的三到四倍（q = 21,000）。在雌性动物中，牛生长激素和绵羊催乳素的效力均比人生长激素低约20倍。用雌酮处理雄性大鼠产生的细胞表现出与雌性大鼠相同的结合特性。这些结果表明，人生长激素与雄性大鼠肝细胞中的促生长受体结合。在雌性大鼠和经雌激素处理的雄性大鼠中，结合人生长激素的受体既能识别生乳特性，也能识别促生长特性。这表明人生长激素在大鼠中的生乳和促生长作用是由不同的受体介导的。
