Functions as a coactivator for aryl hydrocarbon and nuclear receptors (NR). Recruited to promoters through its contact with the N-terminal basic helix-loop-helix-Per-Arnt-Sim (PAS) domain of transcription factors or coactivators, such as NCOA2. During ER-activation acts synergistically in combination with other NCOA2-binding proteins, such as EP300, CREBBP and CARM1. Involved in the transcriptional activation of target genes in the Wnt/CTNNB1 pathway. Functions as a secondary coactivator in LEF1-mediated transcriptional activation via its interaction with CTNNB1. Coactivator function for nuclear receptors and LEF1/CTNNB1 involves differential utilization of two different activation regions. In association with CCAR1 enhances GATA1- and MED1-mediated transcriptional activation from the gamma-globin promoter during erythroid differentiation of K562 erythroleukemia cells (PubMed:24245781). Part of a calphoglin complex consisting of CALCOCO1, PPA1 and PGM (By similarity). Interacts with the bHLH-PAS domains of GRIP1, AHR and ARNT. Interacts with CTNNB1 via both its N- and C-terminal regions. Interacts with EP300. Interacts with CCAR1 (via N-terminus) and GATA1. Shuttles between nucleus and cytoplasm. Expressed in all tissues examined except spleen, with high levels of expression in the heart and kidney. The C-terminal activation region (AD) is used for downstream signaling. Seems to be essential for coactivator function with nuclear receptors and with the aryl hydrocarbon receptor. The N-terminal activation region (AD) is necessary and sufficient for synergistic activation of LEF1-mediated transcription by CTNNB1. Contains a EP3000 binding region which is important for synergistic cooperation. Recruitment by nuclear receptors is accomplished by the interaction of the coiled-coiled domain with p160 coactivators. Belongs to the CALCOCO family.