FIG. 3.

The HERV-K LTR is a TATA-less promoter with a core promoter different from the predicted one. (A) Putative HERV-K LTR structure predicted in the literature and 3′-deletion constructs. The putative TATA box motif is indicated. (B) Promoter competence of the 3′-deletion constructs was determined in GH and Mel-C9 cells and compared to that of the pGL3_pck30 promoter. % RLU are shown as means ± SD for nine individual transfections. The 3′ deletions within the putative R region induced significant losses of promoter activity (pGL3_pcK30dI and -dK). No promoter activity was seen with the predicted U3 core promoter region (pGL_pck30dA). (C) When the TATA motif was mutated to TTTTTTT (pck30dT), the promoter function was significantly enhanced in GH and Mel-C9 cells.