Novel pharmacology of substance K-binding sites: a third type of tachykinin receptor.
The tachykinins are a family of peptides with the carboxyl terminal amino acid sequence Phe-X-Gly-Leu-Met-NH2. Three major mammalian tachykinins have been identified--substance K, neuromedin K, and substance P--but only two tachykinin receptors have been postulated. Three tachykinins were labeled with radioiodinated Bolton-Hunter reagent and their binding characteristics were determined in crude membrane suspensions from several tissues. In cerebral cortex labeled eledoisin exhibited high-affinity binding that was inhibited by tachykinins in a manner indicating a definitive SP-E receptor site. In gastrointestinal smooth muscle and bladder, high-affinity binding of labeled substance P was inhibited in a pattern indicating a definitive SP-P site. In intestinal smooth muscle and bladder, however, labeled substance K and labeled eledoisin were both bound in a pattern indicating a preference for substance K itself. The results suggest the existence of three distinct types of tachykinin receptors: SP-P, SP-E, and SP-K.
D000818:Animals; D001667:Binding, Competitive; D002462:Cell Membrane / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism*; D004386:Duodenum / Q000378:metabolism*; D006168:Guinea Pigs; D007421:Intestine, Small / Q000378:metabolism*; D007700:Kinetics; D051379:Mice; D009928:Organ Specificity; D010455:Peptides / Q000378:metabolism*; D051381:Rats; D018041:Receptors, Neurokinin-2; D017981:Receptors, Neurotransmitter / Q000378:metabolism*; D018039:Receptors, Tachykinin; D013045:Species Specificity; D015320:Tachykinins; D001743:Urinary Bladder / Q000378:metabolism*
D010455:Peptides; D018041:Receptors, Neurokinin-2; D017981:Receptors, Neurotransmitter; D018039:Receptors, Tachykinin; D015320:Tachykinins; C043490:eledoisin receptor