A 64 kd protein was shown to bind to RNAs that contain functional polyadenylation signals by a UV crosslinking procedure in which label was transferred from RNA substrate to protein in cell-free polyadenylation extracts. The 64 kd nuclear protein bound specifically to three different substrates (adenovirus type 5 L3, SV40 early, and SV40 late polyadenylation domains), as determined by competition experiments and partial protease analysis. Deleted derivatives of the SV40 late substrate that retained the sequence 5′-CUGCAAUAA-ACAAGUU-3′ were able to bind the 64 kd polypeptide. This sequence contains the canonical AAUAAA element that has been shown to be indispensable for polyadenylation. A single nucleotide change, converting AAUAAA to AAUAAA, prevented binding of the 64 kd moiety. The 64 kd protein was shown to be distinct from poly(A) polymerase by biochemical fractionation.
All Science Journal Classification (ASJC) codes
- Biochemistry, Genetics and Molecular Biology(all)