|
| |
|
|
|
|
||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
|
Fig. 7. Schematic of interactions occurring between the S2 and S4 helices in the
open and closed states in the jShak1 and QIF channels. (A)jShak1 in closed
state (left) is stabilized by charge-pair interactions between positively
charged R291 and K294 on the S4 helix and negatively charged E237 on S2 and
D260 on S3. In the transition to the open state the interactions between R291
and the two acidic residues are broken and R291 comes into proximity to N227,
which is uncharged. In the N227E mutant the open state is stabilized by the
R291–E227 charge interaction, shifting the equilibrium toward the open
state. (B)In the QIF mutation, where glutamine occupies the position normally
taken by R291, there are no charge interactions between the glutamine residue,
E237 and D260 to stabilize the closed state, so the equilibrium is shifted
towards the open state. Replacement of N227 with acidic residues does not
increase stabilization of the open state because the glutamine does not
interact strongly with the acidic residues.
|
