IR laser-induced perturbations of the voltage-dependent solute carrier protein SLC26a5

Biophys J. 2013 Oct 15;105(8):1822-8. doi: 10.1016/j.bpj.2013.09.008.


Alterations in membrane capacitance can arise from linear and nonlinear sources. For example, changes in membrane surface area or dielectric properties can modify capacitance linearly, whereas sensor residues of voltage-dependent proteins can modify capacitance nonlinearly. Here, we examined the effects of fast temperature jumps induced by an infrared (IR) laser in control and prestin (SLC26a5)-transfected human embryonic kidney (HEK) cells under whole-cell voltage clamp. Prestin's voltage sensor imparts a characteristic bell-shaped, voltage-dependent nonlinear capacitance (NLC). Temperature jumps in control HEK cells cause a monophasic increase in membrane capacitance (Cm) regardless of holding voltage due to double-layer effects. Prestin-transfected HEK cells, however, additionally show a biphasic increase/decrease in Cm with a reversal potential corresponding to the voltage at peak NLC of prestin (Vh), attributable to a rapid temperature-following shift in Vh, with shift rates up to 14 V/s over the course of a 5 ms IR pulse. Treatment with salicylate, a known inhibitor of NLC, reestablishes control cell behavior. A simple kinetic model recapitulates our biophysical observations. These results verify a voltage-dependent protein's ability to respond to fast temperature perturbations on a par with double-layer susceptibility. This likely arises from prestin's unique ability to move sensor charge at kilohertz rates, which is required for the outer hair cells' role as a cochlear amplifier.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anion Transport Proteins / metabolism*
  • Electric Capacitance
  • HEK293 Cells
  • Humans
  • Infrared Rays*
  • Kinetics
  • Lasers*
  • Models, Biological
  • Sulfate Transporters
  • Temperature


  • Anion Transport Proteins
  • SLC26A5 protein, human
  • Sulfate Transporters