Transcription regulator of hematopoietic cell differentiation (PubMed:17934067). Binds gamma-satellite DNA (PubMed:17135265; PubMed:19141594). Plays a role in the development of lymphocytes; B- and T-cells. Binds and activates the enhancer (delta-A element) of the CD3-delta gene. Repressor of the TDT (fikzfterminal deoxynucleotidyltransferase) gene during thymocyte differentiation. Regulates transcription through association with both HDAC-dependent and HDAC-independent complexes. Targets the 2 chromatin-remodeling complexes; NuRD and BAF (SWI/SNF); in a single complex (PYR complex); to the beta- globin locus in adult erythrocytes. Increases normal apoptosis in adult erythroid cells. Confers early temporal competence to retinal progenitor cells (RPCs) (By similarity). Function is isoform-specific and is modulated by dominant-negative inactive isoforms (PubMed:17135265; PubMed:17934067). {ECO:0000250|UniProtKB:Q03267; ECO:0000269|PubMed:10204490; ECO:0000269|PubMed:17135265; ECO:0000269|PubMed:17934067; ECO:0000269|PubMed:19141594}.