Major calcium-binding protein of the Golgi which may have a role in calcium homeostasis (By similarity). Acts as a non-receptor guanine nucleotide exchange factor which binds to and activates alpha subunits of guanine nucleotide-binding proteins (G proteins) (By similarity).
Subcellular locations: Golgi apparatus, Cis-Golgi network membrane, Cytoplasm, Secreted
A small fraction of the protein may be cytoplasmic.