GNPDA1, catalyzes the conversion of glucosamine-6-phosphate to fructose-6-phosphate, a reaction that under physiological conditions proceeds to the formation of fructose-6-phosphate. GNPDA1 is widely expressed with highest expression in testes, ovary and heart. GNPDA1 triggers calcium oscillations in mammalian eggs. These oscillations are as the necessary trigger for egg activation and early development of the embryo.