Increases DNTT terminal deoxynucleotidyltransferase activity (in vitro). Also acts as a transcriptional regulator, binding to the consensus sequence 5'-GNTGCATG-3' following an AT-tract. Associates with RAB20 promoter and positively regulates its transcription. Binds DNA and nucleosomes; may recruit HDAC1 complexes to nucleosomes or naked DNA. Monomer and homodimer. A minor proportion may form homotrimers. Interacts with ZNF541. Interacts with the terminal deoxynucleotidyltransferase DNTT. Interacts with TRERF1. Identified in a histone deacetylase complex that contains DNTTIP1, HDAC1 and MIDEAS; this complex assembles into a tetramer that contains four copies of each protein chain. Component of a histone deacetylase complex containing DNTTIP1, ZNF541, HDAC1 and HDAC2. The N-terminal domain mediates dimerization. The C-terminal domain mediates interaction with DNA and nucleosomes. It contains a HTH motif that mediates recognition of the consensus sequence.