title: New kappa opioid receptor from zebrafish Danio rerio.
abstract: A cDNA that encodes a kappa opioid receptor like from zebrafish (ZFOR3) has been cloned and characterized. The encoded protein is 377 residues long and presents 70% identity with the mammalian kappa receptors, although less homology is found in the amino- and carboxyl-terminus as well as in the extracellular loops. In situ hybridization studies have revealed that ZFOR3 mRNA is highly expressed in particular brain areas that coincide with the expression of the kappa opioid receptor in other species. When ZFOR3 is stably expressed in HEK293 cells, [(3)H]-diprenorphine binds with high affinity (K(D)=1.05+/-0.26 nM), being this value on the same range as those reported for mammalian kappa opioid receptors. On the other hand, the selective agonist for mammalian kappa receptors U69,593 does not bind to ZFOR3. [(3)H]-diprenorphine binding is readily displaced by the peptidic ligand dynorphin A and by the non-endogenous compounds bremazocine, naloxone and morphine, although with different affinities. Our results demonstrate that ZFOR3 is a unique model to study the kappa opioid receptor functionality.
authors.affiliation: Department of Biochemistry and Molecular Biology, Faculty of Medicine, Instituto de Neurociencias de Castilla y Leon, University of Salamanca, Avda. Alfonso X El Sabio s/n, 37007 Salamanca, Spain.
authors.forename: Franscisco Alvar
authors.initials: FA
authors.lastname: Alvarez
authors.forename: Ivan
authors.initials: I
authors.lastname: Rodriguez-Martin
authors.forename: Veronica
authors.initials: V
authors.lastname: Gonzalez-Nuñez
authors.forename: Ezequiel
authors.initials: E
authors.lastname: Marrón Fernández de Velasco
authors.forename: Rogelio
authors.initials: R
authors.lastname: Gonzalez Sarmiento
authors.forename: Raquel E
authors.initials: RE
authors.lastname: Rodríguez
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D001921:Brain / Q000033:anatomy & histology / Q000378:metabolism; D002460:Cell Line; D006801:Humans; D017403:In Situ Hybridization; D008024:Ligands; D008969:Molecular Sequence Data; D011869:Radioligand Assay; D017473:Receptors, Opioid, kappa / Q000096:biosynthesis / Q000235:genetics* / Q000302:isolation & purification; D017386:Sequence Homology, Amino Acid; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D008024:Ligands; D017473:Receptors, Opioid, kappa; D029961:Zebrafish Proteins; C514224:or128-5 protein, zebrafish