|Alternate Names:||NAD(P) transhydrogenase, pyridine nucleotide transhydrogenase|
|Structure and Function:||
NNT is a mitochondrial inner membrane protein catalyzing the interconversion of NADH and NADPH within the matrix space of the organelle. It couples this reaction to proton translocation across the inner membrane. In the presence of an electrochemical proton gradient the production of NADPH is strongly favored. NADPH is required in the mitochondrial matrix to keep the ratio GSH:GSSG high via the NADPH dependent glutathione reductase. Thus NNT has an important role to play in defences against oxidative stress produced by the organelle.
A novel, unexpected role of NNT is in insulin secretion. The absence of NNT prevents glucose from closing the K+ATP channel and from opening the Ca++ channel in pancreatic beta cells. These defective beta cells also show a profound increase in ROS.