Published on April 25, 1990 in J Biol Chem volume 265(12).

PubMed ID: 2324099

DOI: S0021-9258(19)39221-X

Abstract:

Apolipoprotein (apo) B-48 mRNA is produced by in vivo RNA editing which involves aC----U conversion of the first base of the codon CAA for Gln-2153, changing it toUAA, an in-frame stop codon. We have reproduced the editing reaction in vitro usingnuclear extracts. Efficient RNA editing was demonstrated by using apoB mRNA segmentsas substrate or in a coupled transcription-editing reaction using apoB minigenes astemplate. ApoB minigenes were constructed by ligating the adenovirus major latepromoter to a fragment of apoB-100 DNA containing the editing site and used for thetranscription-editing reaction. We defined the sequence specificity of the editingreaction using site-specific single and multiple base mutants constructed by thepolymerase chain reaction. Among 22 different mutant apoB-100 minigene constructscontaining mutations in the bases immediately flanking the edited C-6666, 20 wereedited in the coupled transcription-editing reaction. The results suggest arelatively lax sequence specificity for apoB mRNA editing. Our observation may haveimportant implications for apoB-48 biogenesis as well as for the editing process asa general biologic regulatory mechanism.