The alternative oxidase of the inner mitochondrial membrane catalyses
cyanide-insensitive respiration in plants and fungi. The molecular bio
logy and regulation of this oxidase have been intensively studied over
the past 10 years. Genes have been isolated, expression has been inve
stigated and novel mechanisms for the regulation of activity have been
discovered. This paper reviews these recent advances, focusing on the
regulation of gene expression and activation by protein modification
and organic acids, and possible roles of the alternative oxidase are d
iscussed.