Skip to main content
. Author manuscript; available in PMC: 2010 Apr 12.
Published in final edited form as: Ann N Y Acad Sci. 2008 Dec;1147:321–334. doi: 10.1196/annals.1427.006

Figure 1.

Figure 1

Nuclear respiratory factors (NRF-1 and NRF-2) in the expression of nuclear genes governing mitochondrial respiratory function. NRFs act on the majority of nuclear genes that specify subunits of the five respiratory complexes of the mitochondrial inner membrane. In addition, they act on many other genes whose products direct the expression and assembly of the respiratory apparatus. Promoters for most of the nuclear genes encoding mtDNA transcription and replication factors have functional recognition sites for NRF-1, NRF-2, or both. These factors are required for the expression of respiratory subunits from complexes I, III, IV, and V encoded by mtDNA. Similarly, genes for mitochondrial translational components—including ribosomal proteins and tRNA synthetases as well as heme biosynthetic enzymes localized to the mitochondrial matrix—are NRF-dependent. Increasing evidence also suggests that a number of genes specifying proteins of the mitochondrial protein import and assembly machinery are NRF targets, including subunits of the import receptor complexes and COX assembly factors. Thus, NRF-1 and NRF-2 are part of a unifying mechanism for the coordinate transcriptional control of respiratory chain expression. MRP = mitochondrial RNA processing; POL = polymerase; TOM = translocase of the outer mitochondrial membrane; cytc = cytochrome c.