Mechanism of GTP hydrolysis by G-protein alpha subunits.
Proc Natl Acad Sci U S A
; 91(21): 9828-31, 1994 Oct 11.
Article
em En
| MEDLINE
| ID: mdl-7937899
ABSTRACT
Hydrolysis of GTP by a variety of guanine nucleotide-binding proteins is a crucial step for regulation of these biological switches. Mutations that impair the GTPase activity of certain heterotrimeric signal-transducing G proteins or of p21ras cause tumors in man. A conserved glutamic residue in the alpha subunit of G proteins has been hypothesized to serve as a general base, thereby activating a water molecule for nucleophilic attack on GTP. The results of mutagenesis of this residue (Glu-207) in Gi alpha 1 refute this hypothesis. Based on the structure of the complex of Gi alpha 1 with GDP, Mg2+, and AlF-4, which appears to resemble the transition state for GTP hydrolysis, we believe that Gln-204 of Gi alpha 1, rather than Glu-207, supports catalysis of GTP hydrolysis by stabilization of the transition state.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Guanosina 5'-O-(3-Tiotrifosfato)
/
Proteínas de Ligação ao GTP
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GTP Fosfo-Hidrolases
/
Guanosina Trifosfato
Limite:
Humans
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Ano de publicação:
1994
Tipo de documento:
Article