ABSTRACT
Voltage Dependent Anion Channel (VDAC) in the cell membrane transports important molecules and ions across the cell membrane. It was recently shown that VDAC also acts as a trans membrane NADH dehydrogenase. A recent study showed that autistic children have increased antibodies to VDAC proteins and such a binding inhibits both the transport and dehydrogenase activities of VDAC. The derived function of VDAC, therefore, might underlie the development of autism. It has also recently been shown that the dehydrogenase in erythrocyte membranes requires coenzyme Q. Since the plasma membrane oxidase is not in erythrocyte membranes, the coenzyme Q requirement must be for VDAC. This is consistent with sensitivity of the dehydrogenase to SH inhibitors. This is a novel site for coenzyme Q function but it has an analogy with the Q requirement for the mitochondrial uncoupler protein and the permeability transition pore.
Subject(s)
Autistic Disorder/enzymology , Ubiquinone/metabolism , Cell Membrane/enzymology , Escherichia coli/genetics , Ferricyanides/metabolism , Humans , Mutation , Oxidation-Reduction , Ubiquinone/geneticsABSTRACT
For more than 20 years, the observation that impermeable oxidants can stimulate cell growth has not been satisfactorily explained. The discovery of sirtuins provides a logical answer to the puzzle. The NADH-dependent transplasma membrane electron transport system, which is stimulated by growth factors and interventions such as calorie restriction, can transfer electrons to external acceptors and protect against stress-induced apoptosis. We hypothesize that the activation of plasma membrane electron transport contributes to the cytosolic NAD(+) pool required for sirtuin to activate transcription factors necessary for cell growth and survival.