Original Publication Date
The Biophysical Journal
DOI of Original Publication
Date of Submission
Voltage-sensing domains (VSDs) are membrane protein modules found in ion channels and enzymes that are responsible for a large number of fundamental biological tasks, such as neuronal electrical activity. The VSDs switch from a resting to an active conformation upon membrane depolarization, altering the activity of the protein in response to voltage changes. Interestingly, numerous studies describe the existence of a third distinct state, called the relaxed state, also populated at positive potentials. Although some physiological roles for the relaxed state have been suggested, little is known about the molecular determinants responsible for the development and modulation of VSD relaxation. Several lines of evidence have suggested that the linker (S3-S4 linker) between the third (S3) and fourth (S4) transmembrane segments of the VSD alters the equilibrium between resting and active conformations. By measuring gating currents from the Shaker potassium channel, we demonstrate here that shortening the S3-S4 linker stabilizes the relaxed state, whereas lengthening the linker or splitting it and coinjecting two fragments of the channel have little effect. We propose that natural variations of the length of the S3-S4 linker in various VSD-containing proteins may produce differential VSD relaxation in vivo.
From The Biophysical Journal, Priest, M.F., Lacroix, J.J., Villalba-Galea, C.A., et al., S3-S4 Linker Length Modulates the Relaxed State of a Voltage-Gated Potassium Channel, Vol. 105, Page 2312, Copyright © 2013 Biophysical Society. Published by Elsevier Inc. Reprinted with permission.
Is Part Of
VCU Physiology and Biophysics Publications