Interaction of hnRNP A1 with snRNPs and pre-mRNAs: evidence for a possible role of A1 RNA annealing activity in the first steps of spliceosome assembly.
AUTOR(ES)
Buvoli, M
RESUMO
The in vitro interaction of recombinant hnRNP A1 with purified snRNPs and with pre-mRNAs was investigated. We show that protein A1 can stably bind U2 and U4 snRNP but not U1. Oligo-RNAse H cleavage of U2 nucleotides involved in base pairing with the branch site, totally eliminates the A1-U2 interaction. RNase T1 protection and immunoprecipitation experiments demonstrate that recombinant protein A1 specifically binds the 3'-end regions of both beta-globin and Ad-2 introns. However, while on the beta-globin intron only binding to the polypyrimidine tract was observed, on the Ad-2 intron a 32 nt fragment encompassing the branch point and the AG splice-site dinucleotide was bound and protected. Such protection was drastically reduced in the presence of U2 snRNP. Altogether these results indicate that protein A1 can establish a different pattern of association with different pre-mRNAs and support the hypothesis that this protein could play a role in the annealing of U2 to the branch site and hence in the early events of pre-splicing complex assembly.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=334278Documentos Relacionados
- Crosslinking of hnRNP proteins to pre-mRNA requires U1 and U2 snRNPs.
- RNA binding specificity of hnRNP A1: significance of hnRNP A1 high-affinity binding sites in pre-mRNA splicing.
- An intron element modulating 5' splice site selection in the hnRNP A1 pre-mRNA interacts with hnRNP A1.
- Phosphorylation of human hnRNP protein A1 abrogates in vitro strand annealing activity.
- Function of conserved domains of hnRNP A1 and other hnRNP A/B proteins.