An evolutionarily conserved U5 snRNP-specific protein is a GTP-binding factor closely related to the ribosomal translocase EF-2.
EMBO J
; 16(13): 4092-106, 1997 Jul 01.
Article
em En
| MEDLINE
| ID: mdl-9233818
ABSTRACT
The driving forces behind the many RNA conformational changes occurring in the spliceosome are not well understood. Here we characterize an evolutionarily conserved human U5 small nuclear ribonucleoprotein (snRNP) protein (U5-116kD) that is strikingly homologous to the ribosomal elongation factor EF-2 (ribosomal translocase). A 114 kDa protein (Snu114p) homologous to U5-116kD was identified in Saccharomyces cerevisiae and was shown to be essential for yeast cell viability. Genetic depletion of Snu114p results in accumulation of unspliced pre-mRNA, indicating that Snu114p is essential for splicing in vivo. Antibodies specific for U5-116kD inhibit pre-mRNA splicing in a HeLa nuclear extract in vitro. In HeLa cells, U5-116kD is located in the nucleus and colocalizes with snRNP-containing subnuclear structures referred to as speckles. The G domain of U5-116kD/Snu114p contains the consensus sequence elements G1-G5 important for binding and hydrolyzing GTP. Consistent with this, U5-116kD can be cross-linked specifically to GTP by UV irradiation of U5 snRNPs. Moreover, a single amino acid substitution in the G1 sequence motif of Snu114p, expected to abolish GTP-binding activity, is lethal, suggesting that GTP binding and probably GTP hydrolysis is important for the function of U5-116kD/Snu114p. This is to date the first evidence that a G domain-containing protein plays an essential role in the pre-mRNA splicing process.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fatores de Alongamento de Peptídeos
/
Ribonucleoproteína Nuclear Pequena U5
/
Sequência Conservada
/
Proteínas de Ligação ao GTP
Tipo de estudo:
Prognostic_studies
Limite:
Animals
/
Humans
Idioma:
En
Revista:
EMBO J
Ano de publicação:
1997
Tipo de documento:
Article
País de afiliação:
Alemanha