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Titolo:
Comparison of the amino acid residues in the sixth transmembrane domains accessible in the binding-site crevices of mu, delta, and kappa opioid receptors
Autore:
Xu, W; Li, J; Chen, CG; Huang, P; Weinstein, H; Javitch, JA; Shi, L; de Riel, JK; Liu-Chen, LY;
Indirizzi:
Temple Univ, Sch Med, Dept Pharmacol, Philadelphia, PA 19140 USA Temple Univ Philadelphia PA USA 19140 armacol, Philadelphia, PA 19140 USA Temple Univ, Sch Med, Ctr Subst Abuse Res, Philadelphia, PA 19140 USA Temple Univ Philadelphia PA USA 19140 use Res, Philadelphia, PA 19140 USA Temple Univ, Sch Med, Fels Inst Mol Biol & Canc Res, Philadelphia, PA 19140 USA Temple Univ Philadelphia PA USA 19140 anc Res, Philadelphia, PA 19140 USA Mount Sinai Sch Med, Dept Physiol & Biophys, New York, NY USA Mount Sinai Sch Med New York NY USA Physiol & Biophys, New York, NY USA Columbia Univ Coll Phys & Surg, Ctr Mol Recognit, New York, NY USA Columbia Univ Coll Phys & Surg New York NY USA ecognit, New York, NY USA
Titolo Testata:
BIOCHEMISTRY
fascicolo: 27, volume: 40, anno: 2001,
pagine: 8018 - 8029
SICI:
0006-2960(20010710)40:27<8018:COTAAR>2.0.ZU;2-E
Fonte:
ISI
Lingua:
ENG
Soggetto:
MEMBRANE-SPANNING SEGMENT; DOPAMINE D2 RECEPTOR; 3RD EXTRACELLULAR LOOP; ACTIVATED PROTEIN-KINASE; ALPHA-HELICES; SELECTIVITY; RHODOPSIN; LIGANDS; EXPRESSION; CLONING;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
63
Recensione:
Indirizzi per estratti:
Indirizzo: Liu-Chen, LY Temple Univ, Sch Med, Dept Pharmacol, 3420 N Broad St, Philadelphia, PA 19140 USA Temple Univ 3420 N Broad St Philadelphia PA USA 19140 140 USA
Citazione:
W. Xu et al., "Comparison of the amino acid residues in the sixth transmembrane domains accessible in the binding-site crevices of mu, delta, and kappa opioid receptors", BIOCHEM, 40(27), 2001, pp. 8018-8029

Abstract

We have mapped the residues in the sixth transmembrane domains (TMs 6) of the mu, delta, and kappa opioid receptors that are accessible in the binding-site crevices by the substituted cysteine accessibility method (SCAM). Wepreviously showed that ligand binding to the C7.38S mutants of the mu and kappa receptors and the wild-type delta receptor was relatively insensitiveto methanethiosulfonate ethylammonium (MTSEA), a positively charged sulfhydryl-specific reagent. These MTSEA-insensitive constructs were used as the templates, and 22 consecutive residues in TM6 (excluding C6.47) of each receptor were mutated to cysteine, 1 at a time. Most mutants retained binding affinities for [H-3]diprenorphine, a nonselective opioid antagonist, similar to that of the template receptors. Treatment with MTSEA significantly inhibited [H-3]diprenorphine binding to 11 of 22 mutants of the rat mu receptor and 9 of 22 mutants of the human delta receptor and 10 of 22 mutants of the human kappa receptor. Naloxone or diprenorphine protected all sensitive mutants, except the A6.42(287)C mu mutant. Thus, V6.40, F6.44, W6.48, I6.51, Y6.54, V6.55, I6.56, I6.57, K6.58, and A6.59 of the mu receptor; F6.44, I6.51, F6.54, V6.55, I6.56, V6.57, W6.58, T6.59, and L6.60 of the 6 receptor; and F6.44, W6.48, I6.51, F6.54, I6.55, L6.56, V6.57, E6.58, A6.59, and L6.60 of the kappa receptor are on the water-accessible surface of the binding-site crevices. The accessibility patterns of residues in the TMs 6 of themu, delta, and kappa opioid receptors are consistent with the notion that the TMs 6 are in alpha -helical conformations with a narrow strip of accessibility on the intracellular side of 6.54 and a wider area of accessibilityon the extracellular side of 6.54, likely due to a proline kink at 6.50 that bends the helix in toward the binding pocket and enables considerable motion in this region. The wider exposure of residues 6.55-6.60 to the binding-site crevice, combined with the divergent amino acid sequences, is consistent with the inferred role of residues in this region in determining ligand binding selectivity. The conservation of the accessibility pattern on thecytoplasmic side of 6.54 suggests that this region may be important for receptor activation. This accessibility pattern is similar to that of the D2 dopamine receptor, the only other GPCR in which TM6 has been mapped by SCAM. That opioid receptors and the remotely related D2 dopamine receptor have similar accessibility patterns in TM6 suggest that these segments of GPCRs in the rhodopsin-like subfamily not only share secondary structure but alsoare packed similarly into the transmembrane bundle and thus have similar tertiary structure.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 28/01/20 alle ore 21:19:09