Abstract
Cholecystokinin (CCK) receptors on rat pancreatic acinar cells display two binding affinity states in the presence of adeninine and guanine triphosphates with the effect of ATP mediated by the enzyme nucleoside diphosphate kinase. To determine whether this behavior was intrinsic to a single receptor protein we studied the binding affinity of CHO cells stably transfected with a cloned rat CCK, receptor. 125I-CCK binding to intact cells at 37°C revealed two affinity states for CCK of K(d) values 20 pM and 2.4 nM. Membranes prepared from these cells displayed a single affinity state for CCK but two affinity states could be restored in the presence of GTP[γS], ATP and ATP[γS] but not AMP-PCP. ATP and ATP[γS] but not AMP-PCP were substrates for nucleoside diphosphate kinase present in CHO cell membranes and transferred their terminal phosphate to GDP. These findings indicate that the interconvertible affinity states of the CCK receptor are inherent in a single receptor protein and that nucleoside diphosphate kinase mediates the effect of ATP to regulate these two affinity states
Original language | English (US) |
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Pages (from-to) | 87-93 |
Number of pages | 7 |
Journal | Regulatory Peptides |
Volume | 61 |
Issue number | 2 |
DOIs | |
State | Published - Feb 22 1996 |
Keywords
- ATP
- Cholecystokinin receptor
- GTP
- Nucleoside diphosphate kinase
ASJC Scopus subject areas
- Biochemistry
- Physiology
- Endocrinology
- Clinical Biochemistry
- Cellular and Molecular Neuroscience