Functional role of N-terminal amino acid mutation in CRACM3-N(M1) chimera and CRACM3. Average CRAC current densities at −80 and +130 mV induced by 20 µM IP3 in stable STIM1-expressing HEK293 cells transiently overexpressing point mutation or chimera. Black bars indicate the application of an external solution containing 50 µM 2-APB. Error bars indicate SEM. (A and C) Magnified plot of the initial 120-s data from B and D. (B) CRACM3-N(M1) (black; n = 6), CRACM3-N(M1)-K78E (blue; n = 6), and CRACM3-N(M1)-K85E (red; n = 6). (D) CRACM3-R52E (green; n = 8), CRACM3-R53E (blue; n = 8), CRACM3-K60E (red; n = 7), and CRACM3-K60Q (orange; n = 9). (E–H) Average I-V relationships of CRAC currents extracted from representative HEK293 cells shown in A–D and obtained at 120 s (E and G) and at 180 s (F and H), when current was activated by 2-APB. Data represent leak-subtracted current densities (pA/pF) evoked by 50-ms voltage ramps from −150 to +150 mV.
