STIM-TRP pathways the STIM1/Orai/TRPC channels multiple Ca2+ influx complexes

Abstract

Receptor-evoked Ca2+ influx is a central component of the Ca2+ signal. A ubiquitous form of Ca2+ influx is activated by depletion of endoplasmic Ca2+ stores, the SOC channels. The two established Ca2+ influx channels that are activated by depletion of the endoplasmic reticulum Ca2+ store are the TRPC channels and the newly discovered Orai channels. The two channels can function independently and are gated by different STIM1 domains. Yet, the two channels also affect the function of each other by competition for STIM1 and by yet unresolved mechanism in which their function is required for their mutual activity. This chapter will discuss the evidence for the regulation of the Orai and TRPC channels by STIM1 and the interrelations between the two activities. The function and properties of the Orai channels and their regulation by STIM1 is extensively covered in other chapters and will only be briefly discussed here as they relate to the function of TRPC channels.