So, I've been researching cellular respiration on my own, and trying to keep track of most of the major processes. However, I do have one question left: I can't seem to find any sort of information about how Coenzyme A (I think it's made in the cytosol) is transferred to the matrix (the inside of the mitochondria, inside the inner membrane). Is it transported with a shuttle like for NAD+/NADH, a translocase like for ATP/ADP, or something else? Thank you for your time.

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    $\begingroup$ Good question, to which I cannot find the answer. I doubt whether it is a shuttle, because the nature of shuttles is that they don't transport the difficult bits. There is a carnitine shuttle for transporting acylCoA across the inner mitochondrial membrane, but it transports the acyl-carnitine, not the CoA. The mammalian enzymes for CoA synthesis were only identified this century, so I don't think it's text book stuff. $\endgroup$ – David Nov 23 '17 at 22:32

Zhyvoloup et al. (2003) J Biol Chem 278: 50316-50321; emphasis mine:

CoA synthase is localized on the mitochondrial outer membrane. Moreover, we demonstrate for the first time that phosphatidylcholine and phosphatidylethanolamine, which are the main components of the mitochondrial outer membrane, are potent activators of both enzymatic activities of CoA synthase in vitro. Taken together, these data provide the evidence that the final stages of CoA biosynthesis take place on mitochondria and the activity of CoA synthase is regulated by phospholipids.


  • $\begingroup$ Thank you for the great information on CoA synthesis! However, the article doesn't seem to have any information on how that CoA is brought into the matrix. Do you have anything on the mechanism on which CoA is transported through the inner membrane of the mitochondria? $\endgroup$ – Tesseract Nov 24 '17 at 21:38
  • $\begingroup$ Since "the inner mitochondrial membrane is impermeable to low-molecular-weight solutes [such as CoA, acetyl-CoA, carnitine and acetyl-carnitine]," CoA must be first acylated by "a long-chain-length ATP-specific fatty acyl-CoA synthetase (EC ... associated with the outer-membrane." --Haddock et al. (1970) Biochem J 119: 565-73. ncbi.nlm.nih.gov/pubmed/5500317 $\endgroup$ – user37894 Nov 25 '17 at 8:04

enter image description here I think this can clear your doubt...As it shows how the transport is done between the matrix and cytosol.. And it also explains the presence of coenzyme A ie CoA SH at both the sites.

  • $\begingroup$ It would be great to source this answer... as it stands, it doesn't have any authoritative references. Thanks! $\endgroup$ – rotaredom Feb 7 at 18:29

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