Bobby Sox Homolog (BBX)

HBP2, a new mammalian protein that complements the fission yeast MBF transcription complex. The mammalian HBP2 gene has been isolated by functional complementation of cells unable to undergo DNA replication in fission yeast. HBP2 is a protein with a high mobility group (HMG) domain that belongs to the Sox (Sry-related HMG box) family of transcription factors. As in other members of the family, the HMG box in HBP2 is a DNA-binding domain that is essential for its function in Schizosaccharomyces pombe. Expression of HBP2 in fission yeast activates CdclO-dependent transcription at G1/S and allows growth of cdc10-129, resldelta and rep2delta mutant cells at the restrictive temperature. The mammalian HBP2 activates transcription at G1/S in the fission yeast Sch. pombe.