ATP Flux Is Controlled by a Voltage-gated Channel from the Mitochondrial Outer Membrane

Abstract

A voltage-gated channel, called VDAC (mitochondrial porin) is known to be responsible for most of the metabolite flux across the mitochondrial outer membrane. Here, direct measurements of ATP flux through VDAC channels reconstituted into planar phospholipid membranes establish that VDAC is sufficient to provide passage for ATP efflux from mitochondria. Further, the gating of the channel can shut down ATP flux completely while, simultaneously, allowing the flow of small ions. Thus, these channels are ideally suited to control ATP flux through the mitochondrial outer membrane and, consequently, mitochondrial function. The block to ATP flow through the closed state is likely to be not steric but electrostatic. A voltage-gated channel, called VDAC (mitochondrial porin) is known to be responsible for most of the metabolite flux across the mitochondrial outer membrane. Here, direct measurements of ATP flux through VDAC channels reconstituted into planar phospholipid membranes establish that VDAC is sufficient to provide passage for ATP efflux from mitochondria. Further, the gating of the channel can shut down ATP flux completely while, simultaneously, allowing the flow of small ions. Thus, these channels are ideally suited to control ATP flux through the mitochondrial outer membrane and, consequently, mitochondrial function. The block to ATP flow through the closed state is likely to be not steric but electrostatic.