RNase H catalyzes the precise cleavage of the bonds linking the primer tRNA attached to the minus-strand DNA, the 3' PPT RNA primer to the plus-strand strong-stop DNA, and the cPPT primer to the stretch of plus-strand DNA whose synthesis it primed. In each case, precise cleavage near the RNA-DNA junction occurs (Pullen et al. 1992). HIV-1 RT is the only reverse transcriptase that cleaves the tRNA:DNA junction so as to leave a ribo A residue from the tRNA at the 5' end of the minus strand.
While a single RT heterodimer could in principle catalyze DNA synthesis and primer RNA:DNA bond cleavage, evidence from several in vitro systems suggests that separate RT heterodimers are likely to catalyze these two reactions (Rausch and Le Grice 2004).