AHNAK1 (Desmoyokin) is a large (700 kDa) scaffold protein that translocates to the plasma membrane after an increas of extracellular calcium level or upon proteinkinase C activation and regulates extracellular calcium influx mediated by L-type Ca2+ channels. AHNAK1 has been implicated in diverse signal transduction proceses affecting cell differentiation and proliferation. In response to calcium-dependent intercellular contacts AHNAK1 forms multimeric complexes in the plasma membrane, connected with actin and annexin 2/S100A10 assemblies and is thus involved in organization of the plasma membrane architecture. In epithelial cells, AHNAK1 is localized in cytoplasm or is membrane-associated, but in cells of nonepithelial origin AHNAK1 is predominantly nuclear; it has a weak DNA-binding activity and associates with the DNA-ligase IV-XRCC4 complex.