Superoxide activates a GDP-sensitive proton conductance in skeletal muscle mitochondria from king penguin (Aptenodytes patagonicus).

Abstract We present the partial nucleotide sequence of the avian uncoupling protein (avUCP) gene from king penguin ( Aptenodytes patagonicus ), showing that the protein is 88–92% identical to chicken ( Gallus gallus ), turkey ( Meleagris gallopavo ), and hummingbird ( Eupetomena macroura ). We show that superoxide activates the proton conductance of mitochondria isolated from king penguin skeletal muscle. GDP abolishes the superoxide-activated proton conductance, indicating that it is mediated via avUCP. In the absence of superoxide there is no GDP-sensitive component of the proton conductance from penguin muscle mitochondria demonstrating that avUCP plays no role in the basal proton leak.