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. Author manuscript; available in PMC: 2013 Sep 1.
Published in final edited form as: Biochim Biophys Acta. 2011 Dec 8;1819(9-10):1080–1087. doi: 10.1016/j.bbagrm.2011.11.008

Figure 4. Lon protease degrades TFAM to stabilize the TFAM: mtDNA ratio.

Figure 4

A, Upon reduction of mtDNA copy number in normal cells, Lon degrades TFAM to normalize the TFAM: mtDNA ratio. As a result of this process, mtDNA transcription occurs normally. B, Upon mtDNA reduction in Lon-depleted cells, TFAM is not degraded, resulting in a dramatic increase in the TFAM: mtDNA ratio. This results in a severe inhibition in mtDNA transcription, which is likely caused by mtDNA overpackaging by TFAM. C, Excess TFAM overexpression leads to an increase in the TFAM: mtDNA ratio, resulting in a severe inhibition in mtDNA transcription.