FIG. 4.

Effects of a 5′ cap on cleavage of an RNA oligonucleotide by the RNase H of HIV-1 RT. A 12-base-long RNA was synthesized in vitro that either had, or did not have, a 5′ cap. The RNAs were labeled by including [α³²P]UTP in the synthesis mix. The full-length RNAs were purified by gel electrophoresis and hybridized to DNA oligonucleotides. The resulting heteroduplexes were incubated with HIV-1 RT for various lengths of time (0.25 to 16 min), and the reaction products were fractionated on a 15% polyacrylamide–7 M urea gel.