FIG. 7.

Deletion mapping of the HERV-K RT domain. (A) The HERV-K RT gene of clone 10.1, which expresses a relatively active RT enzyme, was used as the starting material for the generation of a nested set of 5′- and 3′-truncated RT proteins. Indicated are the amino acid positions, with those of clone 10.1 being arbitrarily set at 1 to 595. The position of the YIDD motif within the catalytic core (positions 192 to 195) and the putative position of the RT-RNase H border are indicated. (B) The different RT enzymes were expressed in E. coli as GST fusion proteins and visualized by Western blotting with the GST-specific antiserum. See Fig. 4 for further details. Note that a different protein marker was used in lane 1. This set of RT proteins was tested in the poly(rA)-oligo(dT) assay for enzyme activity. The relative RT activity is listed in panel A, with the activity of the “full-length” RT clone 10.1 being arbitrarily set at 1.0.