STRUCTURE OF THE MR 140,000 GROWTH HORMONE-DEPENDENT INSULIN-LIKE GROWTH-FACTOR BINDING-PROTEIN COMPLEX - DETERMINATION BY RECONSTITUTION AND AFFINITY-LABELING
STRUCTURE OF THE MR 140,000 GROWTH HORMONE-DEPENDENT INSULIN-LIKE GROWTH-FACTOR BINDING-PROTEIN COMPLEX - DETERMINATION BY RECONSTITUTION AND AFFINITY-LABELING
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DOI：
10.1073/pnas.86.18.6898
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发表时间：
1989-09-01
影响因子：
11.1
通讯作者：
MARTIN, JL
中科院分区：
文献类型：
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作者：
BAXTER, RC;MARTIN, JL
为了确定人血清中胰岛素样生长因子（IGF-I和IGF-II）与其结合蛋白之间的高分子量、生长激素依赖性复合物的结构，我们从其纯化的组分蛋白中重构复合物，并在共价交联后通过凝胶电泳和放射自显影对其进行分析。在重构混合物中测试的蛋白质是酸不稳定的Mr 84，000 - 86，000糖蛋白双联体（α）。亚基），具有IGF结合活性的酸稳定Mr 47，000 - 53，000糖蛋白双联体（BP-53或β-亚基）。亚基）和IGF-I或IGF-II（γ亚基）。亚单位）。在含有三个125 I标记的亚基中的任何一个和另外两个未标记的亚基的孵育中，相同的125 I标记的α-。β-。γ的形成了140，000人的复合体。还观察到Mr 120，000和90，000的次要条带，认为代表α-的部分去糖基化形式。β-。γ的复合物和α-。γ的作为交联人工制品产生的复合物。当来自不同生长激素状态的受试者的血清样品用IGF-II示踪剂亲和标记时，观察到生长激素依赖性Mr 140，000，对应于重构的α-IGF-II。β-。γ的复杂.其他生长依赖性标记条带，Mr 90，000（对应于α-β-γ-Al 2 O3）。γ），Mr 55，000 - 60，000（对应于标记的β-亚基双联体）和Mr 38，000、28，000和23，000 - 25，000的较小条带（对应于标记的β-亚基双联体）。亚基降解产物）也见于亲和标记的血清样品和由纯蛋白质重构的复合物中。所有这些都是用抗BP-53抗血清免疫沉淀的。我们得出结论，人血清中的生长激素依赖性Mr 140，000 IGF结合蛋白复合物具有三种组分：（酸不稳定的）亚基，β（结合）亚基;和γ（生长因子）亚基。
To determine the structure of the high molecular weight, growth hormone-dependent complex between the insulin-like growth factors (IGF-I and IGF-II) and their binding proteins in human serum, we have reconstituted the complex from its purified component proteins and analyzed it by gel electrophoresis and autoradiography after covalent cross-linking. The proteins tested in reconstitution mixtures were an acid-labile Mr 84,000-86,000 glycoprotein doublet (.alpha. subunit), an acid-stable Mr 47,000-53,000 glycoprotein doublet with IGF-binding activity (BP-53 or .beta. subunit), and IGF-I or IGF-II (.gamma. subunit). In incubations containing any one of the three subunits 125I-labeled and the other two unlabeled, identical 125I-labeled .alpha.-.beta.-.gamma. complexes of Mr 140,000 were formed. Minor bands of Mr 120,000 and 90,000 were also seen, thought to represent a partially deglycosylated form of the .alpha.-.beta.-.gamma. complex, and an .alpha.-.gamma. complex arising as a cross-linking artifact. When serum samples from subjects of various growth hormone status were affinity-labeled with IGF-II tracer, a growth hormone-dependent Mr 140,000 and was seen, corresponding to the reconstituted .alpha.-.beta.-.gamma. complex. Other growth hormone-dependent labeled bands, of Mr 90,000 (corresponding to .alpha.-.gamma.), Mr 55,000-60,000 (corresponding to labeled .beta.-subunit doublet), and smaller bands of Mr 38,000, 28,000, and 23,000-25,000 (corresponding to labeled .beta.-subunit degradation products), were also seen in the affinity-labeled serum samples and in the complex reconstituded from pure proteins. All were immunoprecipitable with an anti-BP-53 antiserum. We conclude that the growth hormone-dependent Mr 140,000 IGF-binding protein complex in human serum has three components: the .alpha. (acid-labile) subunit, the .beta.(binding) subunit; and the .gamma. (growth factor) subunit.