人生长激素与兔肾微粒体部分的结合
Human somatotropin binding to rabbit kidney microsomal fraction.
作者信息
Roguin L P, Sánchez S H, Bonifacino J S, Paladini A C
出版信息
Biochem J. 1981 Nov 15;200(2):257-64. doi: 10.1042/bj2000257.
Specific binding of 125I-labelled human somatotropin was demonstrated in microsomal membranes (microsomes) from rat and rabbit kidneys. Female rabbit kidney microsomes showed the highest binding activity and were used for further study. The association of 125I-labelled human somatotropin was time- and temperature-dependent and the binding reaction was reversible. Scatchard analysis of saturation data indicated a dissociation equilibrium constant, KD, of 56 pM and a binding capacity of 37 fmol per mg of protein. Similar results were obtained from competition experiments. Binding of 125I-labelled human somatotropin to the microsomes was specifically inhibited by hormones with lactogenic activity. The binding sites, as well as 125I-labelled human somatotropin, were not inactivated on incubation. Treatment of the microsomes with trypsin and chymotrypsin decreased the specific binding by over 90%. Preheating of the microsomes at 55 degrees C for 15 min abolished 50% of the specific binding activity.
在大鼠和兔肾脏的微粒体膜（微粒体）中证实了¹²⁵I标记的人生长激素的特异性结合。雌性兔肾脏微粒体显示出最高的结合活性，并用于进一步研究。¹²⁵I标记的人生长激素的结合是时间和温度依赖性的，并且结合反应是可逆的。对饱和数据的Scatchard分析表明，解离平衡常数KD为56 pM，每毫克蛋白质的结合容量为37 fmol。竞争实验也得到了类似的结果。具有催乳活性的激素可特异性抑制¹²⁵I标记的人生长激素与微粒体的结合。结合位点以及¹²⁵I标记的人生长激素在孵育时不会失活。用胰蛋白酶和胰凝乳蛋白酶处理微粒体可使特异性结合降低90%以上。将微粒体在55℃预热15分钟可消除50%的特异性结合活性。
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