Dinucleotide Sequences at the 5' Ends of Vaccinia Virus mRNA's Synthesized In Vitro

The diversity of dinucleotide sequences at the 5′ ends of vaccinia virus mRNA's was determined by a two-dimensional electrophoresis procedure. RNA labeled with S-adenosylmethyl-³H]methionine was synthesized in vitro by enzymes present in vaccinia virus cores. The RNA, ending in m⁷G(5′)pppN^mpN−, was β-eliminated and treated with alkaline phosphatase. After digestion with RNases T₂, T₁, and A, all eight possible dinucleotides containing G^m and A^m were identified. They are, in decreasing order of abundance: G^mpUp (22%), A^mpCp (18%), G^mpAp (16%), G^mpCp (15%), A^mpAp (11%), A^mpUp (10%), A^mpGp (7%), and G^mpGp (2%).