Single-Channel Recording of a Store-Operated Ca 2+ Channel in Jurkat T Lymphocytes

Abstract
In T lymphocytes, a store-operated calcium ion (Ca 2+ ) entry mechanism termed the calcium release–activated Ca 2+ channel (CRAC channel) underlies the sustained or oscillatory intracellular calcium concentration signal required for interleukin-2 gene expression and cell proliferation. The use of sodium ions as a current carrier enabled single-channel recordings of CRAC channels during activation, inactivation, and blockade of current in the presence of divalent cations. A large conductance of 36 to 40 picosiemens indicates that 100 to 400 CRAC channels are present in T lymphocytes.