Huang S C, Fortune K P, Wank S A, Kopin A S, Gardner J D
Department of Internal Medicine, St. Louis University Health Sciences Center, Missouri 63104.
J Biol Chem. 1994 Oct 21;269(42):26121-6.
We transfected COS cells with cDNA for rat cholecystokinin-A (CCK-A) and different CCK-B receptors and measured binding of 125I-CCK-8, [3H]L-364,718 and [3H]L-365,260 to characterize the different affinity states for each type of CCK receptor. Rat CCK-A and CCK-B receptors, canine CCK-B receptors and canine mutant CCK-B (M-CCK-B) receptors in which the leucine in position 355 was replaced by valine each existed in three different affinity states for CCK-8, high affinity, low affinity, and very low affinity. In rat CCK-A and probably CCK-B receptors, most were in the very low affinity state, whereas with canine CCK-B and M-CCK-B receptors, most were in the low affinity state. Studies with CCK receptor agonists, CCK-8, gastrin, and CCK-JMV-180, in conjunction with CCK receptor antagonists, L-364,718 and L-365,260, showed a different pattern of affinities for these ligands at the different CCK receptors. Thus, each transfected CCK receptor can exist in three different affinity states for CCK-8 and has a characteristic pattern of interaction with different ligands. This ability to exist in multiple affinity states is an intrinsic property of the CCK receptor molecule itself.
我们用大鼠胆囊收缩素-A（CCK-A）和不同的CCK-B受体的cDNA转染COS细胞，并测定125I-CCK-8、[3H]L-364,718和[3H]L-365,260的结合情况，以表征每种类型CCK受体的不同亲和状态。大鼠CCK-A和CCK-B受体、犬CCK-B受体以及第355位亮氨酸被缬氨酸取代的犬突变CCK-B（M-CCK-B）受体对CCK-8均存在三种不同的亲和状态，即高亲和、低亲和和极低亲和。在大鼠CCK-A受体以及可能的CCK-B受体中，大多数处于极低亲和状态，而犬CCK-B和M-CCK-B受体中，大多数处于低亲和状态。使用CCK受体激动剂CCK-8、胃泌素和CCK-JMV-180，结合CCK受体拮抗剂L-364,718和L-365,260进行的研究表明，这些配体在不同CCK受体上具有不同的亲和模式。因此，每种转染的CCK受体对CCK-8可存在三种不同的亲和状态，并且与不同配体具有独特的相互作用模式。这种存在多种亲和状态的能力是CCK受体分子本身的固有特性。
