Emtner M, Roos P
Department of Biochemistry, University of Uppsala, Sweden.
Acta Endocrinol (Copenh). 1990 Mar;122(3):296-302. doi: 10.1530/acta.0.1220296.
A binding protein for growth hormone in serum from female rats has been identified and partially characterized. Serum was incubated with 125I-labelled human GH and fractionated on an agarose HPLC column. Complexes between the binding protein and 125I-hGH were detected as a peak eluted at a volume corresponding to a relative molecular weight of 159,000 +/- 11,000 (N = 8). The peak was not seen when the incubation was carried out in the presence of excess unlabelled hGH. The 125I-hGH bound with high affinity (Ka = 0.87 +/- 0.3 l/nmol; N = 3) and the binding was time- and dose-dependent. Bound 125I-hGH was displaced by rat GH and bovine GH, but not by rat prolactin. The protein was not detected in radioreceptor assay by the commonly used polyethylene glycol precipitation technique and was not recognized by a monoclonal antibody raised against lactogenic receptors from female rat liver. Covalent cross-linking of 125I-hGH to serum revealed in SDS electrophoresis two labelled complexes with molecular weights of 62,300 +/- 3900 and 77,600 +/- 4100, respectively (N = 10).
已鉴定并部分表征了来自雌性大鼠血清中的生长激素结合蛋白。将血清与¹²⁵I标记的人生长激素孵育，并在琼脂糖高效液相色谱柱上进行分级分离。结合蛋白与¹²⁵I-hGH之间的复合物被检测为在对应于相对分子量为159,000±11,000（N = 8）的体积处洗脱的峰。当在过量未标记的hGH存在下进行孵育时，未观察到该峰。¹²⁵I-hGH以高亲和力结合（Ka = 0.87±0.3 l/nmol；N = 3），且结合具有时间和剂量依赖性。结合的¹²⁵I-hGH被大鼠生长激素和牛生长激素取代，但不被大鼠催乳素取代。通过常用的聚乙二醇沉淀技术在放射受体测定中未检测到该蛋白，并且它不被针对雌性大鼠肝脏催乳素受体产生的单克隆抗体识别。¹²⁵I-hGH与血清的共价交联在SDS电泳中显示出两种标记复合物，分子量分别为62,300±3900和77,600±4100（N = 10）。
