Transcriptional repressor (By similarity). Enhances MBD2-mediated repression. Efficient repression requires the presence of GATAD2A (By similarity). Targets MBD3 to discrete loci in the nucleus (By similarity). Plays a role in synapse development (By similarity). Interacts with MBD2 and MBD3 (By similarity). Interaction with MBD2 is required for the enhancement of MBD2-mediated repression and for targeting to the chromatin (By similarity). Component of the MeCP1 histone deacetylase complex (By similarity). Interacts with histone tails, including that of histones H2A, H2B, H3 and H4 (By similarity). Interacts with ERCC6 (By similarity). Speckled nuclear localization requires both CR1 and CR2 regions. Both CR1 and CR2 regions are required for speckled nuclear localization. May be due to intron retention.