Tetramer composed of an alpha subunit, an alpha' subunit and two beta subunits. Interacts with TCTEX1D3 (By similarity). Interacts with CD163. Also component of a CK2-SPT16-SSRP1 complex composed of SSRP1, SUPT16H, CSNK2A1, CSNK2A2 and CSNK2B, the complex associating following UV irradiation.