Figure 2. Shark K_V properties.

a. Average G–V relationships from currents measured at −30mV following activating pulses at the indicated voltage. Shark K_V1.3 V_a1/2 was −5.4 ± 0.4mV, K_a = 7.6 ± 0.4mV, and human K_V1.3 V_a1/2 was −30.7 ± 0.5mV, K_a = 4.7 ± 0.5mV. n = 10, p < 0.0001 for V_a1/2, two-tailed Student’s t-test.

b. Deactivation kinetics of K_V currents at −30mV normalized to maximal amplitude elicited at 40mV. Arrows indicate when deactivation rates were measured. (Right) Expanded view.

c. Deactivation properties of shark (red) and human (black) K_V1.3 channels. τ values from single exponential fits of deactivation at the indicated voltages following an activating prepulse of 40mV (Right). n = 6, p < 0.0001 for comparison of orthologues across voltage pulses, two-way ANOVA with post hoc Bonferroni test.

d. Normalized currents showing inactivation in response to a 10s 40mV pulse. Average current remaining at the end of 10s step. n = 8, p < 0.0001, two-tailed Student’s t-test.

e. Currents demonstrating differences in cumulative inactivation in shark (red) and human (black) K_V1.3 channels in response to 40mV pulses from −100mV delivered in 5ms intervals. Representative of n = 12.

All data represented as mean ± s.e.m.