High mobility group proteins 1 and 2 bind preferentially to brominated poly(dG-dC).poly(dG-dC) in the Z-DNA conformation but not to other types of Z-DNA.

Three proteins from bull testis, previously thought to be Z-DNA-binding proteins but recently found to recognize brominated poly(dG-dC). poly(dG-dC) by criteria different from the Z-conformation, were partially sequenced. Of these, the 31 kDa protein was identified as a member of the high mobility group 2 protein family, and the 33 kDa protein as a member of the high mobility group 1 protein family. Both proteins had molecular weights approximately 30% higher than expected, indicating considerable posttranslational modification. In contrast, the 58 kDa protein remained unidentified for lack of any significant homology with known protein sequences.