Multiple affinity states of different cholecystokinin receptors.
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.
Huang
S C
SC
Department of Internal Medicine, St. Louis University Health Sciences Center, Missouri 63104.
Fortune
K P
KP
Wank
S A
SA
Kopin
A S
AS
Gardner
J D
JD
D000818:Animals; D001570:Benzodiazepinones / Q000378:metabolism; D002478:Cells, Cultured; D020109:Devazepide; D010671:Phenylurea Compounds; D051381:Rats; D011949:Receptors, Cholecystokinin / Q000737:chemistry / Q000378:metabolism*; D012844:Sincalide / Q000378:metabolism; D013329:Structure-Activity Relationship
D001570:Benzodiazepinones; D010671:Phenylurea Compounds; D011949:Receptors, Cholecystokinin; C058121:L 365260; D020109:Devazepide; D012844:Sincalide