ARID4 subfamily DNA-binding activity is represented here by RBP1 (ARID4A). Amino acid identity within the ARID consensus is 75% between RBP1 (ARID4A) and RBP1L1 (ARID4B), the only other member of this class. The assay shown in Figure 4 indicates that RBP1 also binds DNA without sequence specificity. RBP1 has been characterized as a repressor of E2F-dependent transcription recruited by the retinoblastoma protein (pRb) and can recruit histone deacetylase (19,23,24). RBP1L1 (syn.: SAP180) is also able to repress transcription, at least when tethered to DNA through the Gal DNA-binding domain (25). Both RBP1 and RBP1L1/SAP180 have been found in association with the mSIN3-histone deacetylase complex (19,25).
