Interactions of insulin-like growth factors I and II and multiplication-stimulating activity with receptors and serum carrier proteins.
Interactions of insulin-like growth factors I and II and multiplication-stimulating activity with receptors and serum carrier proteins.
复制标题
胰岛素样生长因子 I 和 II 的相互作用以及增殖刺激活性与受体和血清载体蛋白的相互作用。
作者：
M. Rechler;J. Zapf;S. Nissley;E. Froesch;A. Moses;J. Podskalny;E. Schilling;R. Humbel
胰岛素样生长因子(IGFS)I和II是从人血浆中纯化的，增殖刺激活性(MSA)是从BRL 3A大鼠肝细胞系条件培养液中纯化的多肽，具有相似的生物学和生化性质。我们比较了125I标记和未标记的MSA、IGF-I和IGF-II与四种先前证明具有MSA受体的完整细胞或细胞膜的相互作用：大鼠肝细胞质膜、鸡胚胎成纤维细胞、人成纤维细胞和BRL 3A2细胞。在每种情况下，都证明了125I标记的IGF-I和IGF-II的特异性结合。未标记的IGF-I、IGF-II和MSA对每个125I标记的多肽的结合和平行剂量-反应曲线均有明显的抑制作用。然而，在作为结合竞争性抑制物的未标记多肽的相对效力方面，注意到了显著的差异。我们的结论是，结合抑制的不同特异性反映了IGF受体之间的显著异质性。在大鼠和人的血清中，生长抑素载体蛋白似乎也存在类似的异质性。
Insulin-like growth factors (IGFs) I and II, purified from human plasma, and multiplication-stimulating activity (MSA), purified from media conditioned by the BRL 3A rat liver cell line, are polypeptides with similar biological and biochemical properties. We have compared the interaction of 125I-labeled and unlabeled MSA, IGF-I, and IGF-II with four intact cell or cell membrane preparations previously shown to possess MSA receptors: rat liver plasma membranes, chick embryo fibroblasts, human fibroblasts, and BRL 3A2 cells. In each case, specific binding of 125I-labeled IGF-I and IGF-II was demonstrated. With each 125I-labeled peptide, significant inhibition of binding and parallel dose-response curves were observed with unlabeled IGF-I, IGF-II, and MSA. Striking differences were noted, however, in the relative potencies of the unlabeled peptides as competitive inhibitors of binding. We conclude that the different specificities of binding inhibition reflect a significant heterogeneity among IGF receptors. A similar heterogeneity appears to occur among somatomedin carrier proteins in rat and human sera.