The function of CBFA2T3 (CBFA2/RUNX1 partner transcriptional co-repressor 3, ENSG00000129993) is as follows. Transcriptional corepressor which facilitates transcriptional repression via its association with DNA-binding transcription factors and recruitment of other corepressors and histone-modifying enzymes (PubMed:12559562, PubMed:15203199, PubMed:16966434, PubMed:18456661). Can repress the expression of MMP7 in a ZBTB33-dependent manner (PubMed:23251453). Reduces the protein levels and stability of the transcriptinal regulator HIF1A; interacts with EGLN1 and promotes the HIF1A prolyl hydroxylation-dependent ubiquitination and proteasomal degradation pathway (PubMed:25974097). Contributes to inhibition of glycolysis and stimulation of mitochondrial respiration by down- regulating the expression of glycolytic genes including PFKFB3, PFKFB4, PDK1, PFKP, LDHA and HK1 which are direct targets of HIF1A (PubMed:23840896, PubMed:25974097). Regulates the proliferation and the differentiation of erythroid progenitors by repressing the expression of TAL1 target genes (By similarity). Plays a role in granulocyte differentiation (PubMed:15231665). {ECO:0000250|UniProtKB:O54972, ECO:0000269|PubMed:12183414, ECO:0000269|PubMed:15231665, ECO:0000269|PubMed:16966434, ECO:0000269|PubMed:18456661, ECO:0000269|PubMed:23251453, ECO:0000269|PubMed:23840896, ECO:0000269|PubMed:25974097, ECO:0000303|PubMed:12559562, ECO:0000303|PubMed:15203199}. Isoform 2 functions as an A-kinase-anchoring protein (PubMed:11823486). .