Structural comparison of inactivated Kv channels.
(A-J) Structural superposition of Kv1.2s-W366F pore domain with other inactivated channels: side view with Shaker W434F (A) or Kv1.2-2.1-3m (F). Loop 1 conformational differences with Shaker W434F side view (B), top view (C); or with Kv1.2-2.1-3m side view (G), top view (H). Loop 2 conformational changes with Shaker W434F side view (D), top view (E); Kv1.2-2.1 3m side view (I), top view (J). (K) Table lists of the differences among the inactivated Kv channels. (L) H-bonds among the inactivated Kv channels. Adjacent subunits are shown as different colors, and a dashed black line denotes the subunit boundary. H-bonding patterns affect the stability of the inactivated state and an obvious difference is at the location 32’, where Shaker has Thr and Kv1.2 has Val. The mutation V32’T in the Kv1.2-2.1 background provides a new hydrogen bond that stabilizes the important residue D30’ in the inactivated conformation; this can be seen in the Kv1.2-2.1-3m structure (L, panel 3). Our inactivated Kv1.2s structure (containing V32’) nevertheless shows an H-bond network that includes Y28’ and D30’ along with main-chain atoms, possibly yielding a similar stabilization of the inactivated state (L, panel 1). The inactivated Shaker structure lacks H-bond partners for either Y28’ or D30’, which instead are exposed to solvent; however another H-bond network stabilizes the P-loop-S6 linker (L panel 2).