May function as a coactivator for aryl hydrocarbon and nuclear receptors. Detected in the cytoplasm at stages I- II. Detected in the nucleus and the cytoplasm, except for the germ plasm, of almost all cells in cleaving embryos,. Expressed in the germinal vesicle of oocytes at stages I-III. Expressed in ectodermal and mesodermal cells and their derivatives after stage 10. At stages later than 28, highly expressed in the myotome, spinal cord and notochord (at protein level). Belongs to the CALCOCO family.