title: IR laser-induced perturbations of the voltage-dependent solute carrier protein SLC26a5.
abstract: 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.
authors.affiliation: Department of Surgery (Otolaryngology), Yale University School of Medicine, New Haven, Connecticut.
authors.forename: Oluwarotimi
authors.initials: O
authors.lastname: Okunade
authors.forename: Joseph
authors.initials: J
authors.lastname: Santos-Sacchi
mesh_terms: D027321:Anion Transport Proteins / Q000378:metabolism*; D025802:Electric Capacitance; D057809:HEK293 Cells; D006801:Humans; D007259:Infrared Rays; D007700:Kinetics; D007834:Lasers; D008954:Models, Biological; D000076988:Sulfate Transporters; D013696:Temperature
chemical_list: D027321:Anion Transport Proteins; C498719:SLC26A5 protein, human; D000076988:Sulfate Transporters