title: Spare interactions of highly potent [Arg(14),Lys(15)]nociceptin for cooperative induction of ORL1 receptor activation.
abstract: [Arg(14),Lys(15)]Nociceptin is a very potent for ORL1 receptor, showing a few times stronger binding activity and much more enhanced biological activity than endogenous nociceptin. This synergistic outcome has been suggested to be due to the interaction with the receptor aromatic and/or acidic amino acid residues crucial to receptor activation. In order to identify such receptor residues in the second ORL1 extracellular loop, we prepared a series of recombinant mutant receptors. The mutant receptor Gln205Ala was found to be as active as wild-type ORL1 for both nociceptin and [Arg(14),Lys(15)]nociceptin. In contrast, Asp206Ala and Tyr207Ala exhibited considerably reduced activity for [Arg(14),Lys(15)]nociceptin, exhibiting no synergistic activity enhancement. These results suggest that Asp206 and Tyr207 are directly involved in the interaction with nociceptin-[Arg(14),Lys(15)]. Trp208Ala was found to bind strongly both nociceptin and [Arg(14),Lys(15)]nociceptin, although it elicited no biological activity. All these results indicate that the consecutive amino acid residues Asp206, Tyr207, and Trp208 are critical to the activation of the ORL1 receptor, but not to nociceptin-binding.
authors.affiliation: Laboratory of Structure-Function Biochemistry, Department of Chemistry, Faculty of Sciences, Kyushu University, Fukuoka 812-8581, Japan.
authors.forename: Kaname
authors.initials: K
authors.lastname: Isozaki
authors.forename: Jinglan
authors.initials: J
authors.lastname: Li
authors.forename: Kazushi
authors.initials: K
authors.lastname: Okada
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Nishimura
authors.forename: Ayami
authors.initials: A
authors.lastname: Matsushima
authors.forename: Takeru
authors.initials: T
authors.lastname: Nose
authors.forename: Tommaso
authors.initials: T
authors.lastname: Costa
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Shimohigashi
mesh_terms: D000595:Amino Acid Sequence; D001120:Arginine / Q000378:metabolism*; D001667:Binding, Competitive; D007700:Kinetics; D008239:Lysine / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D018847:Opioid Peptides / Q000378:metabolism / Q000494:pharmacology*; D011957:Receptors, Opioid / Q000378:metabolism*; D000094942:Nociceptin Receptor
chemical_list: D018847:Opioid Peptides; D011957:Receptors, Opioid; C444644:nociceptin, Arg(14)-Lys(15)-; D001120:Arginine; D008239:Lysine; D000094942:Nociceptin Receptor