Characterization of kappa opioid receptors in neurosecretosomes from bovine posterior pituitary.

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Pesce G, Lang MA, Russell JT, Rodbard D, Gainer H

Characterization of kappa opioid receptors in neurosecretosomes from bovine posterior pituitary.

J Neurochem. 1987 Aug;49(2):421-7.

PubMed ID

3037028 [ View in PubMed

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Abstract

The binding properties of opioid receptors on isolated nerve terminals (neurosecretosomes) from bovine posterior pituitaries were characterized. Both [3H]etorphine and [3H]ethylketocyclazocine ([3H]EKC) showed high-affinity binding with complex binding isotherms, consistent with the presence of multiple classes of binding sites. [D-Ala2,D-Leu5]enkephalin showed no specific binding and failed to displace [3H]etorphine at high concentrations, indicating the absence of mu, delta, or benzomorphan (kappa 2) sites. Mathematical modelling of the data suggested the presence of three classes of binding sites. The first was of high affinity with Kd values of 0.9 and 2.0 nM for etorphine and EKC, respectively. The second class of sites appeared to bind etorphine with a KD of 150 nM, and EKC with extremely low affinity (unmeasurable binding). The third class of sites was characterized by KD values of 7 and 2 microM for etorphine and EKC, respectively. These results indicate that the nerve terminals of bovine posterior pituitary contain opioid binding sites of the kappa type. Furthermore, these binding sites appear heterogeneous, consisting of at least two and possibly more subtypes or states.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Etorphine	E3 ubiquitin-protein ligase TRIM13	Protein	Humans	Unknown	Agonist	Details