Ga16 is the only heterotrimeric G protein with a restricted expression pattern in hematopoietic cells. Differentiation of promyelocytic cells leads to decreased expression of Ga16. The G protein is known to couple a large number of G protein-coupled receptors to PLC-b and can lead to production of the secondary messengers diacylglycerol and inositol phosphates. Targeted deletion of Ga15, a mouse orthologue of human Ga16, causes reduced C5a receptor signaling. Ga16 serves as a marker, in addition to CD34, for hematopoietic progenitor cells.