Figure 1.

Basic properties of short linker Shaker constructs. (A) Sequence of the S3-S4 linker of constructs produced on a nonfast-inactivating, nonconducting Shaker background. Deleted residues are marked by asterisks. Linker length is determined using prior findings (12) that suggest the linker extends from residue 330 to 362 in the WT channel. (B) Example of gating currents obtained from short linker construct Sh Δ330–344 in response to the activation protocol shown (prepulse to −120 mV followed by 80 ms long, 10 mV steps from −120 to 40 mV). The trace with the slowest kinetics is highlighted in red. (C) Tau-V (black) and normalized Q-V (blue) of the Sh Δ330–344 construct. The saturated depolarized membrane potential, used in later derelaxation protocols, is marked by the green symbol in the Q-V, at 0 mV for this construct. The slowest activation Tau, or activation τ_max, is about 6 ms for this construct and is marked by the red symbol in the Tau-V. (D) V_1/2 of Q-Vs obtained from activation protocol plotted against linker length. N is between 3 and 9 for each construct; error bars here and in all other figures show standard error. The V_1/2 of Δ341–346 is more hyperpolarized than that of Δ345–350 or Δ330–335, which are roughly equivalent. (E) τ_max obtained from the same protocol, plotted against linker length. N is between 3 and 10 for each construct. Δ330–335 has much slower kinetics than Δ345–350, which is comparable to WT in kinetics, and also slower than Δ341–346, which is the fastest.