Key result
Mutation of the S4-S5 linker lysine (Lys197) to alanine or methionine precluded trafficking of hIK1 and rat SK3 channels to the plasma membrane, retaining them in the endoplasmic reticulum.
A conserved lysine residue in the S4-S5 linker is critical for the correct trafficking of intermediate and small conductance potassium channels to the plasma membrane.
Does not inform clinical channel modulation; leaves open whether S4-S5 linker targeting alters excitability in disease models.
We have investigated the role of the S4-S5 linker in the trafficking of the intermediate (human (h) IK1) and small (rat SK3) conductance K(+) channels using a combination of patch-clamp, protein biochemical, and immunofluorescence-based techniques. We demonstrate that a lysine residue (Lys(197)) located on the intracellular loop between the S4 and S5 domains is necessary for the correct trafficking of hIK1 to the plasma membrane. Mutation of this residue to either alanine or methionine precluded trafficking of the channel to the membrane, whereas the charge-conserving arginine mutation had no effect on channel localization or function. Immunofluorescence localization demonstrated that the K197A mutation resulted in a channel that was primarily retained in the endoplasmic reticulum, and this could not be rescued by incubation at 27 degrees C. Furthermore, immunoblot analysis revealed that the K197A mutation was overexpressed compared with wild-type hIK1 and that this was due to a greatly diminished rate of channel degradation. Co-immunoprecipitation studies demonstrated that the K197A mutation did not preclude multimer formation. Indeed, the K197A mutation dramatically suppressed expression of wild-type hIK1 at the cell surface. Finally, mutation of this conserved lysine in rat SK3 similarly resulted in a channel that failed to correctly traffic to the plasma membrane. These results are the first to demonstrate a critical role for the S4-S5 linker in the trafficking and/or function of IK and SK channels.
No takes yet. Share an insight, caveat, or question.
Jones et al. (2005) studied this question. Mutation of Lys197 in S4-S5 linker vs. Wild-type hIK1 and rat SK3 was evaluated on Channel trafficking to the plasma membrane. Mutation of the S4-S5 linker lysine (Lys197) to alanine or methionine precluded trafficking of hIK1 and rat SK3 channels to the plasma membrane, retaining them in the endoplasmic reticulum.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: