![Structural biparititioning of CDI mediated by distinct CaM lobes. (A) Exemplar currents show strong CDI of DI W[+2]A mutation as evident from accelerated current decay observed with Ca2+ (red) versus Ba2+ (black) currents evoked in response to a 300-ms test pulse. Ca2+ current decay of wild-type CaV1.3 is shown as rose trace to facilitate comparison. Here, measurement obtained in the presence of endogenous CaM and therefore net CDI includes contributions of both N- and C-lobes of CaM. (B and C) DII W[+2]A and DIII W[+2]A mutations minimally perturb CDI. Format as in panel A. (D) CaV1.3 DIV W[+2]A mutation partially diminishes CDI. Here, CDI is measured by comparing inactivation in Ca2+ with endogenous CaM versus CaM1234 coexpressed (blue trace). (E) Population data confirms a mild reduction in CDI observed with W[+2]A mutation. P < 0.001 by Tukey’s multiple comparisons test. Each bar and error, mean ± SEM. n = 7 cells for CaV1.3 wild-type and n = 5 for all mutant channels. (F–J) CDI mediated by the C-lobe of CaM is selectively diminished by CaV1.3 DIV W[+2]A mutation. Here, the component of C-lobe CDI is isolated by coexpression of CaM12. For DIV W[+2]A mutant, we compared inactivation with CaM12 to CaM1234. Red trace, Ca2+ current; black trace, Ba2+ current; rose trace, Ca2+ current from CaV1.3 WT co-expressed with CaM12. Each bar and error, mean ± SEM. n = 6 cells (CaV1.3 wild-type), n = 5 cells (DI W[+2]A), n = 5 cells (DII W[+2]A), n = 6 cells (DIII W[+2]A), and n = 7 cells (DIV W[+2]A). ***P < 0.001 by Tukey’s multiple comparisons test. (K–O) CDI mediated by N-lobe of CaM is diminished by CaV1.3 DI W[+2]A, DII W[+2]A, and DIII W[+2]A mutations. However, DIV W[+2]A increases N-lobe CDI. Here, N-lobe CDI is isolated by coexpression of CaM34. Red trace, Ca2+ current; black trace, Ba2+ current; rose trace, Ca2+ current from CaV1.3 WT co-expressed with CaM34. For DIV W[+2]A mutant, we compared inactivation with CaM34 versus when CaM1234 is coexpressed (blue trace). Each bar and error, mean ± SEM. n = 5 cells (CaV1.3 wild-type), n = 7 cells (DI W[+2]A), n = 7 cells (DII W[+2]A), n = 6 cells (DIII W[+2]A), and n = 7 cells (DIV W[+2]A). ***P < 0.001 by Tukey’s multiple comparisons test.](https://cdn.rupress.org/rup/content_public/journal/jgp/156/2/10.1085_jgp.202313365/1/jgp_202313365_fig5.png?Expires=1769377332&Signature=LYCII19e3gZvimGqduOXYf7RkTVmeuufAvJs7OZxc3VITqOoFfwaxV2fCfrxJ-TO7rvcCSk2ZGxcZPiL7v2NPDo~7sMCYpms0UlWZsj37Qb1JBUqgD6flK5OR-rG~mG~UQdvcGE8kAEO7UVuIfVJ~HERIt~F~WBSb7Y8YhulX-8wC~UVJ9ipKJJImOcoUnDV4sp~iOtA49YlUEK~pQ9qnCPmfW91BxF3CfmcfiMq4Nhnpb2DScqJJyVw8ghHtqjIijEWvDTDBFM8Gf8Jpi3Y7gaHLtA~jjU0KHMTKX2c3Y3PuisxvTb4Q~UKU3AiqMoe3VrGe0RIAkZ9-0fsgSXNEA__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
Structural biparititioning of CDI mediated by distinct CaM lobes. (A) Exemplar currents show strong CDI of DI W[+2]A mutation as evident from accelerated current decay observed with Ca2+ (red) versus Ba2+ (black) currents evoked in response to a 300-ms test pulse. Ca2+ current decay of wild-type CaV1.3 is shown as rose trace to facilitate comparison. Here, measurement obtained in the presence of endogenous CaM and therefore net CDI includes contributions of both N- and C-lobes of CaM. (B and C) DII W[+2]A and DIII W[+2]A mutations minimally perturb CDI. Format as in panel A. (D) CaV1.3 DIV W[+2]A mutation partially diminishes CDI. Here, CDI is measured by comparing inactivation in Ca2+ with endogenous CaM versus CaM1234 coexpressed (blue trace). (E) Population data confirms a mild reduction in CDI observed with W[+2]A mutation. P < 0.001 by Tukey’s multiple comparisons test. Each bar and error, mean ± SEM. n = 7 cells for CaV1.3 wild-type and n = 5 for all mutant channels. (F–J) CDI mediated by the C-lobe of CaM is selectively diminished by CaV1.3 DIV W[+2]A mutation. Here, the component of C-lobe CDI is isolated by coexpression of CaM12. For DIV W[+2]A mutant, we compared inactivation with CaM12 to CaM1234. Red trace, Ca2+ current; black trace, Ba2+ current; rose trace, Ca2+ current from CaV1.3 WT co-expressed with CaM12. Each bar and error, mean ± SEM. n = 6 cells (CaV1.3 wild-type), n = 5 cells (DI W[+2]A), n = 5 cells (DII W[+2]A), n = 6 cells (DIII W[+2]A), and n = 7 cells (DIV W[+2]A). ***P < 0.001 by Tukey’s multiple comparisons test. (K–O) CDI mediated by N-lobe of CaM is diminished by CaV1.3 DI W[+2]A, DII W[+2]A, and DIII W[+2]A mutations. However, DIV W[+2]A increases N-lobe CDI. Here, N-lobe CDI is isolated by coexpression of CaM34. Red trace, Ca2+ current; black trace, Ba2+ current; rose trace, Ca2+ current from CaV1.3 WT co-expressed with CaM34. For DIV W[+2]A mutant, we compared inactivation with CaM34 versus when CaM1234 is coexpressed (blue trace). Each bar and error, mean ± SEM. n = 5 cells (CaV1.3 wild-type), n = 7 cells (DI W[+2]A), n = 7 cells (DII W[+2]A), n = 6 cells (DIII W[+2]A), and n = 7 cells (DIV W[+2]A). ***P < 0.001 by Tukey’s multiple comparisons test.