A sequence-specific RNA-binding protein complements apobec-1 To edit apolipoprotein B mRNA.
Mol Cell Biol
; 18(8): 4426-32, 1998 Aug.
Article
em En
| MEDLINE
| ID: mdl-9671452
The editing of apolipoprotein B (apo-B) mRNA involves the site-specific deamination of cytidine to uracil. The specificity of editing is conferred by an 11-nucleotide mooring sequence located downstream from the editing site. Apobec-1, the catalytic subunit of the editing enzyme, requires additional proteins to edit apo-B mRNA in vitro, but the function of these additional factors, known as complementing activity, is not known. Using RNA affinity chromatography, we show that the complementing activity binds to a 280-nucleotide apo-B RNA in the absence of apobec-1. The activity did not bind to the antisense strand or to an RNA with three mutations in the mooring sequence. The eluate from the wild-type RNA column contained a 65-kDa protein that UV cross-linked to apo-B mRNA but not to the triple-mutant RNA. This protein was not detected in the eluates from the mutant or the antisense RNA columns. Introduction of the mooring sequence into luciferase RNA induced cross-linking of the 65-kDa protein. A 65-kDa protein that interacted with apobec-1 was also detected by far-Western analysis in the eluate from the wild-type RNA column but not from the mutant RNA column. For purification, proteins were precleared on the mutant RNA column prior to chromatography on the wild-type RNA column. Silver staining of the affinity-purified fraction detected a single prominent protein of 65 kDa. Our results suggest that the complementing activity may function as the RNA-binding subunit of the holoenzyme.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Apolipoproteínas B
/
Proteínas de Ligação a RNA
/
Edição de RNA
/
Citidina Desaminase
Limite:
Animals
Idioma:
En
Ano de publicação:
1998
Tipo de documento:
Article