Ca2+: a versatile master key for intracellular signaling cascades

Ca 2+ is one of the most ancient and versatile intracellular messengers in both animal and plant systems.Ca 2+ interacts with a huge array of signaling proteins, and coordinates the integration of non-signaling proteins into cellular communication systems.In doing so, Ca 2+ 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 [1].Ca 2+ also controls the life cycle at various stages, from regulating fertilization and cell growth to modulating programmed cell death (apoptosis).Ca 2+ is unequivocally a master key with the ability to control most cellular processes.This special issue brings together 12 invited reviews of some of the key functions of Ca 2+ in cells, most of which were presented at the 17th International Symposium on Ca 2+ -binding Proteins and Ca 2+ Function in Health and Disease in Beijing, China, on July 16-20, 2011.As reflected in these reviews, the current era of Ca 2+ research is characterized by intense interest in the structure and functional regulation of Ca 2+ transporters and Ca 2+ -binding proteins, and the roles of Ca 2+ in health and disease processes.