Transcriptional coactivator for steroid receptors and nuclear receptors. Coactivator of the steroid binding domain (AF-2) but not of the modulating N-terminal domain (AF-1). Required in a nuclear receptor pathway to suppress expression of dorsal mesoderm genes. May play a role in the positive regulation of the circadian clock. Contains three Leu-Xaa-Xaa-Leu-Leu (LXXLL) motifs. The LXXLL motifs are essential for the association with nuclear receptors and are, at least in part, functionally redundant. The LLXXLXXXL motif is involved in transcriptional coactivation and CREBBP/CBP binding. Contains 2 C-terminal transcription activation domains (AD1 and AD2) that can function independently. Belongs to the SRC/p160 nuclear receptor coactivator family.