Ca2+-dependent regulation of sodium channels NaV1.4 and NaV1.5 is controlled by the post-IQ motif.Yoder, J.B., Ben-Johny, M., Farinelli, F., Srinivasan, L., Shoemaker, S.R., Tomaselli, G.F., Gabelli, S.B., Amzel, L.M.
(2019) Nat Commun 10: 1514-1514
- PubMed: 30944319
- DOI: 10.1038/s41467-019-09570-7
- Primary Citation of Related Structures:
- PubMed Abstract:
Skeletal muscle voltage-gated Na + channel (Na V 1.4) activity is subject to calmodulin (CaM) mediated Ca 2+ -dependent inactivation; no such inactivation is observed in the cardiac Na + channel (Na V 1 ...
Skeletal muscle voltage-gated Na + channel (Na V 1.4) activity is subject to calmodulin (CaM) mediated Ca 2+ -dependent inactivation; no such inactivation is observed in the cardiac Na + channel (Na V 1.5). Taken together, the crystal structures of the Na V 1.4 C-terminal domain relevant complexes and thermodynamic binding data presented here provide a rationale for this isoform difference. A Ca 2+ -dependent CaM N-lobe binding site previously identified in Na V 1.5 is not present in Na V 1.4 allowing the N-lobe to signal other regions of the Na V 1.4 channel. Consistent with this mechanism, removing this binding site in Na V 1.5 unveils robust Ca 2+ -dependent inactivation in the previously insensitive isoform. These findings suggest that Ca 2+ -dependent inactivation is effected by CaM's N-lobe binding outside the Na V C-terminal while CaM's C-lobe remains bound to the Na V C-terminal. As the N-lobe binding motif of Na V 1.5 is a mutational hotspot for inherited arrhythmias, the contributions of mutation-induced changes in CDI to arrhythmia generation is an intriguing possibility.
Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA. firstname.lastname@example.org.