"Alternative" fuels contributing to mitochondrial electron transport: Importance of non-classical pathways in the diversity of animal metabolism

Comp Biochem Physiol B Biochem Mol Biol. 2018 Oct;224:185-194. doi: 10.1016/j.cbpb.2017.11.006. Epub 2017 Nov 15.


The study of glycolysis, the TCA cycle, and oxidative phosphorylation in animals has yielded a wealth of information about bioenergetics. Less is known about how animals use fuels other than glucose and less characterized enzymes that are also used to provide electrons to the electron transport system. It has become clear that bioenergetic flexibility is employed by a wide variety of animals in order to successfully grow, maintain cells, and reproduce, and has contributed to the exploitation of new environments and ecological niches through evolution. In most cases, the discovery of these "alternative" fuels and non-classical pathways is relatively recent, but is starting to call into question long believed paradigms about the diversity of animal bioenergetics. We present several specific examples of these "alternatives" and the animals that use them and present some implications for animal mitochondrial physiology research.

Keywords: Electron transport system; Energetics; Glycerol-3-phosphate dehydrogenase; Insects; Mitochondria; Proline; Proline dehydrogenase.

Publication types

  • Review

MeSH terms

  • Animals
  • Citric Acid Cycle / physiology*
  • Electron Transport / physiology
  • Glycolysis / physiology*
  • Humans
  • Mitochondria / physiology*
  • Oxidative Phosphorylation*