Fig. 3.
STAC3 coexpression abolishes CDI of CaV1.2 but not of CaV2.1 in an IQ domain dependent manner. Representative normalized calcium and barium currents at Vmax of tsA201 cells expressing CaV1.2 (A), CaV2.1 (D), or CaV1.2-IQA (G). Internal calcium buffering with 0.5 mM EGTA. Significant differences in the relative residual current amplitude after 250 ms (Ires250/Ipk) in calcium and barium indicate robust CDI (****P < 0.0001 for CaV1.2; **P = 0.002 for CaV2.1; ****P < 0.0001 for CaV1.2-IQA). (B) Upon coexpression of STAC3, the CDI of CaV1.2 currents was abolished, as in calcium and barium currents inactivated to the same extent and Ires250/Ipk were comparable (n.s., P = 0.82). In contrast, CDI of CaV2.1 and CaV1.2-IQA was unaffected by coexpression of STAC3 (*P = 0.012 and ****P < 0.0001, respectively) (E–H). Representative normalized net CDI (−ICa/IBa) of CaV currents in the absence or the presence of STAC3 and relative Ires250/Ipk demonstrate that STAC3 coexpression abolishes the CDI of CaV1.2 (****P < 0.0001) (C), but not of CaV2.1 and CaV1.2-IQA (n.s., P = 0.32 and P = 0.37, respectively). (F–I) P values are from unpaired t test.