Sodium ion and proline binding sites in the Na+/proline symport carrier of Escherichia coli.
Biochim Biophys Acta
; 1105(1): 61-6, 1992 Mar 23.
Article
em En
| MEDLINE
| ID: mdl-1567896
ABSTRACT
Proline binding activity of the Escherichia coli Na+/proline symport carrier is inhibited by a sulfhydryl reagent, N-ethylmaleimide (NEM). Proline and its analogs protected the carrier against the NEM-inactivation in a Na+ (or Li+)-dependent manner. Na+ alone, even in the absence of proline, partially protected it from the NEM-inactivation. Mutant proline carriers, CS281, CS344 and CS349, which have a serine residue in place of Cys-281, Cys-344 and Cys-349, respectively (Yamato, I. and Anraku, Y. (1988) J. Biol. Chem. 263, 16055-16057) were also analyzed for cation-dependent proline binding and NEM-sensitivity. Proline binding activities of CS281 and CS344 were almost completely resistant to NEM, whereas that of CS349 was not. Furthermore, the proline binding activity of CS344 was remarkably lower than those of the wild-type, CS281 and CS349 carriers. These results indicate that Cys-344, which is located in the putative eighth membrane-spanning domain in the carrier, is a cysteine residue functionally involved in the high-affinity binding for sodium ion and proline.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Sódio
/
Prolina
/
Proteínas de Transporte
/
Proteínas de Escherichia coli
/
Sistemas de Transporte de Aminoácidos Neutros
/
Simportadores
/
Escherichia coli
Idioma:
En
Revista:
Biochim Biophys Acta
Ano de publicação:
1992
Tipo de documento:
Article
País de afiliação:
Japão