Sexton P M, Houssami S, Brady C L, Myers D E, Findlay D M
St. Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia.
Endocrinology. 1994 May;134(5):2103-7. doi: 10.1210/endo.134.5.8156909.
The cloned renal porcine calcitonin (pCT) receptor cDNA expressed by transient transfection in COS-1 cells or stable transfection in HEK-293 cells was assayed for interaction with CT, amylin, and CT gene-related peptide. Both [125I]salmon CT ([125I]sCT) and [125I]rat amylin displayed specific binding to transfected cells, and in both cases, pCT and rat amylin were equipotent in competing for binding. sCT was most potent in binding competition assays, whereas human CT and rat or human CT gene-related peptide did not compete. Despite the greater apparent affinity of sCT for receptor binding, sCT, pCT, and rat amylin had similar efficacies in stimulating the production of cAMP in the stably transfected cell line (EC50, 0.5-1.6 x 10(-9) M). These results contrasted with those obtained with the rat C1a CT receptor, for which amylin did not compete for [125I]sCT binding and stimulated cAMP production only at high concentrations. These results show that pCT and amylin interact with similar potencies with the pCT receptor and suggest that amylin may act as a natural ligand for this receptor.
通过在COS - 1细胞中瞬时转染或在HEK - 293细胞中稳定转染表达的克隆猪肾降钙素（pCT）受体cDNA，检测其与降钙素（CT）、胰淀素和CT基因相关肽的相互作用。[125I]鲑鱼降钙素（[125I]sCT）和[125I]大鼠胰淀素均显示与转染细胞有特异性结合，并且在这两种情况下，pCT和大鼠胰淀素在竞争结合方面具有同等效力。sCT在结合竞争试验中最有效，而人CT以及大鼠或人CT基因相关肽不参与竞争。尽管sCT对受体结合的表观亲和力更高，但sCT、pCT和大鼠胰淀素在刺激稳定转染细胞系中cAMP产生方面具有相似的效力（EC50，0.5 - 1.6×10⁻⁹ M）。这些结果与用大鼠C1a CT受体获得的结果形成对比，对于大鼠C1a CT受体，胰淀素不竞争[125I]sCT结合，并且仅在高浓度下刺激cAMP产生。这些结果表明，pCT和胰淀素与pCT受体相互作用的效力相似，并提示胰淀素可能作为该受体的天然配体。
