Transcriptional coactivator for steroid receptors and nuclear receptors (PubMed:23508108, PubMed:8670870, PubMed:9430642, PubMed:22504882, PubMed:26553876). Coactivator of the steroid binding domain (AF-2) but not of the modulating N-terminal domain (AF-1) (PubMed:23508108, PubMed:8670870, PubMed:9430642). Required with NCOA1 to control energy balance between white and brown adipose tissues (PubMed:23508108, PubMed:8670870, PubMed:9430642). Critical regulator of glucose metabolism regulation, acts as a RORA coactivator to specifically modulate G6PC1 expression (PubMed:23508108, PubMed:8670870, PubMed:9430642). Involved in the positive regulation of the transcriptional activity of the glucocorticoid receptor NR3C1 by sumoylation enhancer RWDD3 (PubMed:23508108). Positively regulates the circadian clock by acting as a transcriptional coactivator for the CLOCK-BMAL1 heterodimer (By similarity). {ECO:0000250|UniProtKB:Q61026, ECO:0000269|PubMed:22504882, ECO:0000269|PubMed:23508108, ECO:0000269|PubMed:26553876, ECO:0000269|PubMed:8670870, ECO:0000269|PubMed:9430642}. This is the function of NCOA2 (nuclear receptor coactivator 2, ENSG00000140396).