Diagram of dynamic distribution of calnuc. There are two pools for caluc: cytosolic and the Golgi membrane associated. Cytosolic calnuc interacts with Gαi subunits on the Golgi and vesicles budded from the Golgi, whereas luminal calnuc retains in the Golgi lumen for several hours, followed by secretion along the constitutive-like pathway. Calnuc binding the Golgi lumen is subjected to post-translational modification, and as the major calcium binding protein, plays a key role in constitution of a calcium pool in the Golgi. Cytosolic calnuc involves distribution of Gαi subunits via binding to them, and further participates regulation of G protein related intracellular pathways.