Fig. 10. Model of Grg4 recruitment by Pax5 (BSAP). (A) Summary of the identified interactions between Pax5 and Grg4. (B) Model ofGrg-mediated gene repression by Pax5. As different members of the Grg family are co-expressed with Pax5 throughout midbrain and B-cell development (Koop et al., 1996; D.Eberhard, unpublished data), we hypothesize that Pax5 can stably recruit Grg proteins to a specific promoter only in collaboration with a second Grg-binding transcription factor (X). CoA, coactivator protein(s); BTM, basal transcription machinery.