Fig. 1 | Nature Communications

Fig. 1

From: Ca2+-dependent regulation of sodium channels NaV1.4 and NaV1.5 is controlled by the post-IQ motif

Fig. 1

C-terminal tail and CaM control of NaV CDI. a Schematic of NaV1.5, NaV1.4 and NaV1.5-CTail1.4 (NaV1.5 residues 1–1773 with NaV1.4 1599–1836) used in experiments below. b Pulse protocol for Na+ channel current recordings and assessment of CDI. The pulse protocol with a 150 msec step to +20 mV (red) activates co-expressed CaV2.1 while a step to −40 mV (black) does not. c Current elicited by the pulse protocols. The Na+ current is probed before (P1) and after (P2) Ca2+ entry into the cells due to the intermediate depolarization at −40 mV (where the Ca2+ channels are closed) and +20 mV (where the Ca2+ channels are open). The pre-pulse P1 and the test pulse P2 are used to probe the Na+ current in the absence of Ca2+ due to the intermediate depolarization at −40 mV or in the presence of Ca2+ due to the activated Ca2+ channels during the further depolarization at +20 mV. d Na+ currents measured during P1 and P2. The P2 current after Ca2+ influx (red trace) compared to P2 current with no Ca2+ influx (black). e Data points of CDI measurement (open circles, filled circle as mean with bars showing ±1 standard deviation) with CaM WT, CaM12 or CaM34 showing only the N-lobe of CaM is required to bind Ca2+ for CDI to occur. Statistical significance was determined by an unpaired t-test. Supplementary Table 2 lists values of the individual data points shown. f Alignment of the sequences of NaV1.4 and NaV1.5 in IQ and post-IQ regions

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