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Titolo:
SHORT EXTERNAL LOOPS AS POTENTIAL SUBSTRATE-BINDING SITE OF GAMMA-AMINOBUTYRIC-ACID TRANSPORTERS
Autore:
TAMURA S; NELSON H; TAMURA A; NELSON N;
Indirizzi:
ROCHE INST MOLEC BIOL,ROCHE RES CTR NUTLEY NJ 07110 ROCHE INST MOLEC BIOL,ROCHE RES CTR NUTLEY NJ 07110 TEL AVIV UNIV,DEPT BIOCHEM IL-69978 TEL AVIV ISRAEL
Titolo Testata:
The Journal of biological chemistry
fascicolo: 48, volume: 270, anno: 1995,
pagine: 28712 - 28715
SICI:
0021-9258(1995)270:48<28712:SELAPS>2.0.ZU;2-N
Fonte:
ISI
Lingua:
ENG
Soggetto:
BRAIN GABA TRANSPORTER; RAT-BRAIN; MOUSE-BRAIN; EXPRESSION; CLONING; PERMEASE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
24
Recensione:
Indirizzi per estratti:
Citazione:
S. Tamura et al., "SHORT EXTERNAL LOOPS AS POTENTIAL SUBSTRATE-BINDING SITE OF GAMMA-AMINOBUTYRIC-ACID TRANSPORTERS", The Journal of biological chemistry, 270(48), 1995, pp. 28712-28715

Abstract

While the gamma-aminobutyric acid (GABA) transporter GAT1 exclusivelytransports GABA, GAT2, -3, and 4 also transport beta-alanine, Cross-mutations in the external loops IV, V, and VI among the various GABA transporters were performed by site-directed mutagenesis. The affinity of GABA transport as well as inhibitor sensitivity of the modified transporters was analyzed, Kinetic analysis revealed that a cross-mutationin which loop IV of GAT1 was modified to resemble GAT4 resulted in increased affinity to GABA from K-m = 8.7 to 2.0 mu M without changing the V-max. A cross mutation in loop VI, which swapped the amino acid sequence of GATE for GAT1, decreased the affinity to GABA (K-m, 35 mu M). These results suggest that loops TV and VI contribute to the bindingaffinity of GABA transporters, A substitution of three amino acids inloop V of GAT1 by the corresponding sequence of GAT3 resulted in beta-alanine sensitivity of its GABA uptake activity, These three amino acids in loop V seem to participate in the beta-alanine binding domain of GAT3. It is suggested that those three external loops (IV, V, and VI) form a pocket in which the substrate binds to the GABA transporters.

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Documento generato il 30/03/20 alle ore 00:18:58