Transcriptional repressor. Enhances MBD2-mediated repression. Efficient repression requires the presence of GATAD2B. Interacts with MBD2 and MBD3 (PubMed:12183469, PubMed:16415179, PubMed:21490301). Interaction with MBD2 is required for the enhancement of MBD2-mediated repression and for targeting to the chromatin (PubMed:12183469, PubMed:16415179, PubMed:21490301). Component of the MeCP1 histone deacetylase complex (PubMed:21490301). Interacts with histone tails, including that of histones H2A, H2B, H3 and H4 (PubMed:16415179). This interaction is reduced by histone acetylation (PubMed:16415179). Interacts with ERCC6 (PubMed:26030138). Speckled nuclear localization requires both CR1 and CR2 regions. Ubiquitous, both in fetal and adult tissues. Both CR1 and CR2 regions are required for speckled nuclear localization. Truncated N-terminus. Truncated N-terminus.