Figure 8. Engineering synthetic modulation of Ca_V1 channels.

(A) Left, schematic shows the atomic structure of Mona SH3 domain in complex with RxxK motif. Right, sequence alignment outlines strategy for insertion of RxxK motif into Ca_V1.3, yielding Ca_V1.3_RxxK to confer synthetic suppression of Ca_V1.3 CDI by Mona SH3. (B–C) Ca_V1.3_S expressed with and without Mona SH3 shows full CDI, confirming that wildtype Ca_V1.3 CDI is insensitive to Mona SH3. Format as in Figure 1A–B. Control data are reproduced from Figure 1D for comparison. (D–E) Mona SH3 strongly diminishes CDI of Ca_V1.3_RxxK. Format as in Figure 1A–B. (F) Cartoon summarizes selective modulation of Ca²⁺/CaM signaling to Ca_V1, and Na_V1 channels with CaM, stac, and fhf.

Figure 8—figure supplement 1. Extended data demonstrate feasibility of engineering synthetic modulators of CaM signaling to Ca_V1.3.

(A) Ca_V1.3_S is insensitive to the SH3 domain of Mona/gads protein. Population data of inactivation r₃₀₀ values show strong CDI of Ca_V1.3_S in the presence of Mona SH3. Format as in Figure 1—figure supplement 1A. (B) In sharp contrast, the introduction of RxxK motif to Ca_V1.3 upstream CI elements (left subpanel) confers synthetic modulation of CaM signaling by Mona SH3. Middle, population r₃₀₀ values show CDI of Ca_V1.3_RxxK under endogenous levels of CaM. Right, co-expression of Mona SH3 abolishes CDI of Ca_V1.3_RxxK, illustrating the feasibility of engineering synthetic regulatory proteins that abolish Ca²⁺/CaM signaling to selected targets. Format as in Figure 1—figure supplement 1A.