EXTRA SPECIFICITY FROM EXTRADENTICLE - THE PARTNERSHIP BETWEEN HOX AND PBX EXD HOMEODOMAIN PROTEINS/

For many DNA-binding transcription factors it is often difficult to re concile their highly specific in vivo function with their less specifi c in vitro DNA-binding properties. Cooperative DNA binding with cofact ors often provides part of the answer to this paradox and recent studi es have demonstrated this to be the case for the homeotic complex (HOX ) family of transcription factors. However, the unique problem posed b y these highly related and developmentally important transcription fac tors requires additional twists to the standard solution, which are be ginning to become apparent from the characterization of the HOX cofact ors encoded by the extradenticle and PBX genes.