TABLE 1.

RNA-dependent DNA polymerase activities of the mutant heterodimers^a

Heterodimerb	Activity (%)
Wild type	100
G190A	170
G190S	120
G190E	20
L74V-G190E	100
V75I-G190E	105
L74V	100
V75I	100

^aIndividual mutations were prepared in RT(66) clones (13, 17) by the method of BspMI cassette mutagenesis as previously described (2, 3). p66-p51 heterodimers were generated and purified as previously described (4). The polymerase assays were done as previously described (4). The reactions used equal amounts of purified p66-p51 heterodimers (2.0 ng) and poly(rC) · oligo(dG) as the substrate. The amount of labeled polymer collected for the wild-type heterodimer was considered 100% activity, and the amounts of labeled polymer collected for the various mutant heterodimers were normalized to this value. 

^bThe heterodimers other than the wild type are designated by the mutations they carry.