Water-soluble specific growth hormone binding sites from cultured human lymphocytes: preparation and partial characterization.
Water-soluble specific growth hormone binding sites from cultured human lymphocytes: preparation and partial characterization.
复制标题
来自培养的人淋巴细胞的水溶性特异性生长激素结合位点：制备和部分表征。
作者：
L. WILLIAM McGUFFIN;R. Gavin;A. Lesniak;P. Gorden;J. Roth
培养的人淋巴细胞（IM-9细胞系）具有人生长激素（hGH）的特异性结合位点或受体。在适当的条件下，这种特异性结合物质自发释放到孵育介质中，并在不使用去污剂的情况下溶解。该水溶性制剂与[125 I]碘-hGH的结合特异性与完整细胞上的受体相同。未标记的hGH（而非猪生长激素或胰岛素）与标记的hGH竞争结合可溶性制剂。不同纯度的生长激素制剂以与它们竞争结合完整IM-9淋巴细胞相同的等级顺序竞争结合可溶性结合制剂。与可溶性制剂孵育但未结合的[125 I]碘-hGH被部分降解，而与可溶性制剂结合的[125 I]碘-hGH被保护免于降解，其重新结合新鲜细胞的能力增强。[125 I]碘-hGH可溶性结合制剂复合物可通过加入大量未标记的hGH或降低pH值解离，在两种情况下，[125 I]碘-hGH均保持完整且未降解。当以200，000 X g离心4小时时，可溶性结合制剂未沉淀，并且未保留在0.20微米Millipore过滤器上。可溶性结合制剂在SephadexG-200上没有延迟。通过胰蛋白酶消化消除结合活性。这些研究表明，生长激素结合位点，如以前报道的胰岛素结合位点，可以自发地溶解从培养的人淋巴细胞，而不使用洗涤剂，这些可溶性结合制剂是高分子量的，并且是，至少部分，蛋白质的性质。
Cultured human lymphocytes (IM-9 cell line) have specific binding sites or receptors for human growth hormone (hGH). Under appropriate conditions, this specific binding material is spontaneously released into the incubation medium and is solubilized without the use of detergents. This water-soluble preparation binds [125I]iodo-hGH with the same specifictiy as receptors on the intact cell. Unlabeled hGH, but not porcine growth hormone or insulin, competes with labeled hGH for binding to the soluble preparation. Growth hormone preparations of varying purity compete for binding to the soluble binding preparation in the same rank order as they compete for binding to the intact IM-9 lymphocyte. [125I]iodo-hGH incubated with, but not bound to, the soluble preparation is partially degraded, while the [125I]iodo-hGH that is bound to the soluble preparation is protected from degradation, and its ability to rebind to fresh cells is enhanced. The [125I]iodo-hGH-soluble binding preparation complex can be dissociated by the addition of large quantities of unlabeled hGH or by lowering the pH, and [125I]iodo-hGH in both instances remains intact and undegraded. The soluble binding preparation did not sediment when centrifuged at 200,000 X g for 4 hours and was not retained on 0.20 micron Millipore filters. The soluble binding preparation was not retarded on Sephadex G-200. Binding activity was abolished by tryptic digestion. These studies demonstrate that hGH-binding sites, like previously reported insulin binding sites, can be spontaneously solubilized from cultured human lymphocytes, without the use of detergents; these soluble binding preparations are of high molecular weight and are, at least in part, protein in nature.