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. 2005 Jan;79(1):67–78. doi: 10.1128/JVI.79.1.67-78.2005

FIG. 1.

FIG. 1.

Enhancer structures of wild-type and mutant SL3-3 MLVs used in the study (24, 25, 26). (A) The SL3-3(wt) enhancer located in U3 consists of a 72-bp direct repeat followed by a third repetition of 34 bp containing binding sites for a variety of transcription factors. Both SL3-3(turbo) and SL3-3(2Δ18-2) harbor two identical 18-bp deletions encompassing the NF1 site. In addition, the SL3-3(turbo) enhancer contains an extra 72-bp wt repeat. SL3-3(GTT) and SL3-3(TUMdm) are both Runx binding site mutants. The SL3-3(GTT) enhancer contains the GTT-to-TGG mutation in both Runx site I binding sites. The SL3-3(TUMdm) enhancer harbors several alterations compared to the SL3-3(wt) enhancer structure. In addition to an extra 72-bp repeat, the enhancer harbors two identical 28-bp deletions encompassing the NF1 site. Furthermore, GTT-to-TGG and GAC-to-TCA mutations are present in Runx site I and site II, respectively. A T-to-G base substitution is present in the last Runx site I. (B) The enhancer structures are illustrated schematically with boxes; deletions are marked by gaps, and Runx binding site mutations are indicated by letters. WT, wild type.