Figure 1.

Sequence homology of Kv subfamily members with minimal gating diagram. (a) shows the sequence alignment of the P-loop (contributing to the SF) in KcsA, Shaker, hKv1.5, hKv2.1, and hKv3.1. The second threonine residue within this filter (indicated in bold) is replaced by alanine in this work. (b) depicts a minimal gating diagram with six states whereby the activated (A) and activated-inactivated (AI) states are intermediate states that the channel transitions to go from closed to open or inactivated and vice-versa. In the nonconductive closed state (C), the SF (S) has an open conformation, whereas the intracellular AG gate (G) is closed. Upon membrane depolarization, the AG converts into an activated and subsequently an open conformation, and the ion channel is conductive (O state). In channels displaying C-type inactivation, prolonged depolarization causes the channel to inactivate (I state) through SF rearrangements and ion conduction is inhibited. Finally, upon closing of the activation gate during repolarization, the channel occupies the closed-inactivated state (CI).