A sequence-specific single-strand-binding protein for the late-coding strand of the simian virus 40 control region

We have purified a protein from uninfected monkey CV1 cells that binds specifically in vitro to the late-coding simian virus 40 DNA strand in the region of transcription control without any detectable binding to the complementary single strand. Nuclease protection experiments detected two binding sites in the 21-base-pair repeat region. The protein did not bind to this region in the double-stranded form, nor did it bind to RNA synthesized in vitro by using either DNA strand as a template. This protein, and perhaps other DNA single-strand-sequence-specific proteins, may play a role in the control of gene expression in higher organisms.