Montiel J L, Berghman L R, Arámburo C
Departamento de Fisiología, Universidad Nacional Autónoma de México, D.F.
Gen Comp Endocrinol. 1992 Nov;88(2):298-306. doi: 10.1016/0016-6480(92)90263-j.
It has been described that pituitary growth hormone shows molecular and functional heterogeneity. In birds, size and charge variants of chicken growth hormone (cGH) have been shown in the chicken pituitary gland and in purified preparations of the hormone. Here we demonstrate the existence of cGH molecular isoforms in chicken serum, thus suggesting that they are secreted from the gland. The isolation of total cGH present in sera was performed by immunoaffinity chromatography employing a specific monoclonal antibody against cGH. Different analytical electrophoretic methods (SDS-polyacrylamide gel electrophoresis, isoelectric focusing, bidimensional polyacrylamide gel electrophoresis) followed by Western blot and immunostaining were employed to characterize the serum cGH isoforms, and compared to those present in a fresh pituitary extract. Several identical immunoreactive bands comigrated in both serum and the gland extract in the different systems (SDS-PAGE, MW 16, 22, 26, 29, 52, 62, 66 kDa; IEF, pIs 8.1, 7.5, 7.1, 6.8, 6.2), thus revealing a high correspondence of molecular isoforms of the hormone in the two tissues. Additionally, a glycosylated variant of chicken growth hormone (G-cGH) was also revealed in the serum after concanavalin A-Sepharose chromatography.
据描述，垂体生长激素显示出分子和功能的异质性。在鸟类中，鸡生长激素（cGH）的大小和电荷变体已在鸡垂体以及该激素的纯化制剂中被发现。在此，我们证明了鸡血清中存在cGH分子异构体，这表明它们是从腺体分泌的。血清中总cGH的分离是通过使用针对cGH的特异性单克隆抗体的免疫亲和色谱法进行的。采用不同的分析电泳方法（SDS-聚丙烯酰胺凝胶电泳、等电聚焦、双向聚丙烯酰胺凝胶电泳），随后进行蛋白质印迹和免疫染色来表征血清cGH异构体，并与新鲜垂体提取物中的异构体进行比较。在不同系统（SDS-PAGE，分子量16、22、26、29、52、62、66 kDa；IEF，等电点8.1、7.5、7.1、6.8、6.2）中，血清和腺体提取物中有几条相同的免疫反应条带迁移，从而揭示了两种组织中该激素分子异构体的高度对应性。此外，在伴刀豆球蛋白A-琼脂糖色谱后，血清中还发现了鸡生长激素的糖基化变体（G-cGH）。
