ABSTRACT
Ca2+ is a ubiquitous and fundamental signaling component that is utilized by cells to regulate a diverse range of critical cellular functions. Typically, cells respond to a Ca2+ signal that is generated inside the cell in response to activation of a wide variety of cell surface receptors, including those involved in neurotransmitter, hormonal, and sensory signaling. In most cases, the initial Ca2+ signal generated in the cell is a speci—c increase in cytoplasmic [Ca2+] ([Ca2+]i) resulting from release of Ca2+ from internal Ca2+ stores (mainly the endoplasmic reticulum [ER]) or entry of Ca2+ from the external medium across the plasma membrane. Both routes involve movement of Ca2+ through Ca2+ channels that are localized within these cellular membranes. While intracellular Ca2+ release from ER occurs via channels activated by inositol 1,4,5-trisphosphate (IP3), cyclic ADP-ribose, or Ca2+ itself, Ca2+ inŸux across the plasma membrane is achieved via numerous types of Ca2+ channels, including voltage-gated Ca2+ channels and store-operated Ca2+ channels, as well as a variety of ligand-gated cation channels, although the type of channels can vary depending on the cell type.1-3Among these, the transient receptor potential (TRP) superfamily of ion channels have been described to be involved in a diverse array of signaling mechanisms that regulate critical sensory functions in cells as well as other processes such as secretion, proliferation, neuronal guidance, cell death, and development.
