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Titolo:
ROLE OF THE EXTRACELLULAR DOMAINS OF THE CHOLECYSTOKININ RECEPTOR IN AGONIST BINDING
Autore:
SILVENTEPOIROT S; ESCRIEUT C; WANK SA;
Indirizzi:
NIDDKD,DIGEST DIS BRANCH,NIH,BLDG 10,ROOM 9C-103 BETHESDA MD 20892 NIDDKD,DIGEST DIS BRANCH,NIH BETHESDA MD 20892 CHU RANGUEIL,INSERM,U151 F-31403 TOULOUSE FRANCE
Titolo Testata:
Molecular pharmacology
fascicolo: 2, volume: 54, anno: 1998,
pagine: 364 - 371
SICI:
0026-895X(1998)54:2<364:ROTEDO>2.0.ZU;2-9
Fonte:
ISI
Lingua:
ENG
Soggetto:
LIGAND-BINDING; FUNCTIONAL EXPRESSION; A RECEPTOR; IDENTIFICATION; ANTAGONIST; RESIDUES; AFFINITY; PURIFICATION; LOCALIZATION; MUTAGENESIS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
35
Recensione:
Indirizzi per estratti:
Citazione:
S. Silventepoirot et al., "ROLE OF THE EXTRACELLULAR DOMAINS OF THE CHOLECYSTOKININ RECEPTOR IN AGONIST BINDING", Molecular pharmacology, 54(2), 1998, pp. 364-371

Abstract

The cholecystokinin (CCK) receptor types A and B (CCKAR and CCKBR) are G protein-coupled receptors with approximately 50% amino acid identity; both have high affinity for the sulfated CCK octapeptide (CCK-8), whereas only the CCKBR has high affinity for gastrin. Previously, we identified five amino acids in the second extracellular loop (ECL) of the CCKBR that were essential for gastrin selectivity. Subsequent mutagenesis of one of these five amino acids (H207F) resulted in the loss of radiolabeled CCK-8 binding. CCK-8 stimulated total inositol phosphate accumulation in COS-1 cells transiently expressing the CCKBR-H207F with full efficacy and a 3044-fold reduced potency, which suggests thatthe loss of radioligand binding was caused by a loss in affinity. Alanine scanning mutagenesis was performed on the amino terminus near thetop of transmembrane domain I (TM) and on ECL1, two extracellular domains implicated in ligand binding by previous mutagenesis studies. (125)-Bolton-Hunter-CCK-8 binding to mutant receptors transiently expressed in COS-1 identified one nonconserved amino acid, R57A, at the top of TMI that caused a 21-fold reduction in CCK-8 affinity and four conserved amino acids, N115A, L116A, F120A and F122A, in the ECL1 that caused a 15.6-, 6-, 440-, and 8-fold reduction in affinity or efficacy. Alanine substitution of the equivalent amino acids in the CCKAR corresponding to each of the five amino acids in ECL1 and ECL2 affecting CCK-8affinity for the CCKBR revealed only two mutations, L103A and F107A, that decreased CCK-8 affinity (68- and 2885-fold, respectively). Thesedata suggest that CCK-8 interacts at multiple contact points in the extracellular domains of CCK receptors and that the CCKAR and CCKBR have distinct binding sites despite their shared high affinity for CCK-8.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 01/10/20 alle ore 16:06:56