Ca2+: a versatile master key for intracellular signaling cascades.

Ca2+ is one of the most ancient and versatile intracellular messengers in both animal and plant systems. Ca2+ interacts with a huge array of signaling proteins, and coordinates the integration of non-signaling proteins into cellular communication systems. In doing so, Ca2+ plays crucial roles in many biological processes, including gene regulation, fuel generation in the metabolic pathways, substance transport across membranes, hormone and neurotransmitter secretion, cell motility and muscle contraction . Ca2+ also controls the life cycle at various stages, from regulating fertilization and cell growth to modulating programmed cell death (apoptosis). Ca2+ is unequivocally a master key with the ability to control most cellular processes.