Regulation of Central Cholecystokinin Recognition Sites by Guanyl Nucleotides |
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Authors: | L Wennogle H Wysowskyj D J Steel B Petrack |
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Institution: | Research Department, CIBA-GEIGY Corporation, Summit, NJ 07901. |
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Abstract: | Guanyl nucleotides affected the binding of radiolabeled cholecystokinin (CCK) octapeptide to rodent cortical binding sites. Micromolar quantities of a stable GTP analogue, guanylyl-imidodiphosphate (GppNp), resulted in a plateau where binding was decreased by 30%. In the presence of 25 microM GppNp, binding analysis revealed a decrease in affinity (increase in KD), without an apparent effect on the maximal number of binding sites. Ki values for CCK-related peptides shifted up to 1.6-fold. The rate of peptide association decreased by threefold, and the rapid component of peptide dissociation increased. The collective data suggest that a class of central CCK binding sites is linked to nucleotide regulatory proteins. The evidence is discussed with regard to multiple receptor populations and to possible interconversions between receptor types. |
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Keywords: | Cholecystokinin Nucleotide regulatory protein Receptors Central nervous system |
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