ABSTRACT
This chapter discusses direct electrophysiological methods used to record the electrical activity of these proteins, focusing on calcium-selective Orai/STIM and TRPV5/TRPV6 channels. Calcium stores inside the cell that were shown to be important for CRAC channel activation and functions are the endoplasmic reticulum and mitochondria. In T lymphocytes and mast cells, store-operated calcium entry is the main pathway providing cytoplasmic calcium elevations necessary for key cellular functions, such as antigenic activation, proliferation, and degranulation. Great advances have been made in the electrophysiological and molecular identification of calcium entry pathways in non-excitable cells. The most common protocol used to record CRAC channels is the application of command voltage ramps spanning -100 to +100 mV. The perforated-patch variety of the whole-cell patch clamp has been successfully used to record CRAC channels. Additionally, in perforated-patch recording, CRAC channels could only be activated by antigen application at 37°C but not at room temperature, unlike the case for SERCA inhibitors.
