Figure 1. Selectivity properties of expressed hexameric and tetrameric Orai1 concatamers.

(a) Mean (±SE, n = 6) I/V curves for store-operated currents recorded between −100 mV and +80 mV in cells expressing the concatenated Orai1 hexamer in an external medium containing 140 mM Na⁺ and either 10 mM Ca²⁺, or 0.1 mM Ca²⁺. (b) The corresponding mean (±SE, n = 5) I/V curves for store-operated currents in cells expressing the concatenated Orai1 tetramer. (c) Western blot showing the expressed FLAG-tagged concatamers running at their appropriate expected molecular masses (approximately 195 kDa for the hexamer, and 130 kDa for the tetramer).