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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 1. AAA+ proteases in the mitochondrial matrix.

Figure 1

Lon, ClpXP and m-AAA are the three major proteases in the animal mitochondrial matrix. Lon and ClpXP localize in the mitochondrial matrix per se, whereas the m-AAA protease is membrane anchored to expose its catalytic site to the matrix space. Lon forms a ring-shaped homo-oligomeric structure, and m-AAA forms homo- or hetero-oligomeric structures. ClpXP is composed of two subunits, ClpP and ClpX; it is a hetero-oligomeric complex in which ClpP forms a two-stack heptameric ring-shaped structure to which two hexameric ClpX rings bind on each side. Some mitochondrial proteins, such as TFAM, mtDNA replication factors, etc., bind to mtDNA to package it into a structure called the mitochondrial nucleoid. Lon is also a component of the mitochondrial nucleoid.