Figure 1.

A, diagrammatic representation of Cav1.1 with voltage sensor mutations highlighted. B, diagrammatic representation of Nav1.4 with voltage sensor mutations highlighted. C, configuration of four domains in each channel to form a single ion-selective pore. *There is evidence that R675G has a gating pore opened by depolarisation. This is in contrast to the gating pore which is open at hyperpolarising potentials for the other SCN4A mutants studied to date. The phenotype of the R675G/Q/W mutants also differs being one of potassium-sensitive normokalaemic periodic paralysis.