High impact information on COX4

• Translational regulation of nuclear gene COX4 expression by mitochondrial content of phosphatidylglycerol and cardiolipin in Saccharomyces cerevisiae [1].
• Substitutions at the Cys ligand positions result in non-functional Cox4 proteins that fail to lead to cytochrome oxidase assembly [2].
• Zn(II) binding in Cox4 is, therefore, important for the stability of the complex [2].
• Cox4 is the only cofactor-containing subunit that is not directly part of the catalytic core of the enzyme located in the mitochondrial inner membrane [2].
• This is not a consequence of reduced membrane potential due to loss of cytochrome oxidase activity because Cox2p C-tail export was not blocked in mitochondria lacking Cox4p [3].

Biological context of COX4

• In addition, the intron contains a nucleotide sequence in which 15 out of 18 nucleotides are identical with a sequence in the intron of COX4, the nuclear gene encoding cytochrome c oxidase subunit 4 [4].
• Isolation and characterization of QCR9, a nuclear gene encoding the 7.3-kDa subunit 9 of the Saccharomyces cerevisiae ubiquinol-cytochrome c oxidoreductase complex. An intron-containing gene with a conserved sequence occurring in the intron of COX4 [4].

Associations of COX4 with chemical compounds

• The solution structure of yeast Cox4 elucidated by multidimensional NMR reveals a C-terminal globular domain consisting of two beta sheets analogous to the bovine ortholog except the loop containing the coordinating His in the yeast protein and the fourth Cys in the bovine protein are in different positions in the two structures [2].

Other interactions of COX4

• One class contains three complementation groups whose strains carry mutations in the COX4, COX5a, or COX9 genes [5].
• Null mutants in COX4, COX5a, or COX6, which encode subunits 4, 5, and 6 of yeast cytochrome oxidase are blocked in assembly of the enzyme [6].

References