Importin alpha binds to an unusual bipartite nuclear localization signal in the heterogeneous ribonucleoprotein type I.
Eur J Biochem
; 269(11): 2727-34, 2002 Jun.
Article
em En
| MEDLINE
| ID: mdl-12047381
ABSTRACT
The heterogeneous nuclear ribonucleoprotein (hnRNP) type I, a modulator of alternative splicing, localizes in the nucleoplasm of mammalian cells and in a discrete perinucleolar structure. HnRNP I contains a novel type of bipartite nuclear localization signal (NLS) at the N-terminus of the protein that we have previously named nuclear determinant localization type I (NLD-I). Recently, a neural counterpart of hnRNP I has been identified that contains a putative NLS with two strings of basic amino acids separated by a spacer of 30 residues. In the present study we show that the neural hnRNP I NLS is necessary and sufficient for nuclear localization and represents a variant of the novel bipartite NLS present in the NLD-I domain. Furthermore, we demonstrate that the NLD-I is transported into the nucleus by cytoplasmic factor(s) with active transport modality. Binding assays using recombinant importin alpha show an interaction with NLD-I similar to that of SV40 large T antigen NLS. Deletion analysis indicates that both stretches of basic residues are necessary for binding to importin alpha. The above experimental results lead to the conclusion that importin alpha acts as cytoplasmic receptor for proteins characterized by a bipartite NLS signal that extends up to 37 residues.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Ribonucleoproteínas
/
Proteínas de Ligação a RNA
/
Sinais de Localização Nuclear
/
Alfa Carioferinas
Tipo de estudo:
Prognostic_studies
Limite:
Humans
Idioma:
En
Revista:
Eur J Biochem
Ano de publicação:
2002
Tipo de documento:
Article
País de afiliação:
Itália