| The interaction of Pax 5 ( BSAP ) with Daxx can result in transcriptional activation in B cells . ^^^ Using a yeast two hybrid assay to identify potential coregulators of Pax 5 , we identified Daxx , a protein that is highly conserved , ubiquitously expressed , and essential for embryonic mouse development . ^^^ The interaction between Pax 5 and Daxx involves the partial homeodomain of Pax 5 and the C terminal fragment of Daxx . ^^^ Upon transient transfection assay of Daxx in B cells expressing endogenous Daxx and Pax 5 , we observed not only transcriptional corepression but also , unexpectedly , coactivation in M12 . 4 . 1 and A 20 mouse B cell lines . ^^^ Coactivation apparently involves recruitment of the CREB binding protein ( CBP ) , because we precipitated complexes containing Pax 5 , Daxx , and CBP in B cell lines . ^^^ |