VDAC-1 ion channel protein, molecular model. This is the human voltage-dependent anion-selective channel protein 1 (VDAC-1). This ion channel, classed as a porin (beta barrel proteins), is found on the outer membrane of mitochondria, the organelles that generate energy in cells. This function of VDAC ion channels is to allow the passage of small hydrophilic molecules. They open and close in response to the voltage across the membrane (membrane potential). This ion channel also acts to inhibit the release of apoptogenic (cell death-inducing) proteins from the mitochondria.