Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.9.3.1 (cytochrome oxidase)
 8,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The RCA1 (YTA12) and AFG3 (YTA10) genes of Saccharomyces cerevisiae code for homologous mitochondrial proteins that belong to the recently described AAA protein-family [Kunau et al. (1993) Biochimie 75,209-224]. Mutations in either gene have been shown to induce a respiratory defect. In the case of rca1 mutants this phenotype has been ascribed to defective assembly of cytochrome oxidase and ubiquinol-cytochrome c reductase. In the present study we show that the respiratory defect of afg3 mutants, like that of rca1 mutants, is also caused by an arrest in assembly of cytochrome oxidase and ubiquinol-cytochrome c reductase. In addition to the absence of the respiratory complexes, rca1 and afg3 mutants exhibit reduced mitochondrial ATPase activity. As a first step to an understanding of the biochemical basis for the ATPase defect we have examined the assembly of the F1 and F0 constituents of the ATPase complex. We present evidence that the ATPase lesion stems at least in part from the failure of rca1 and afg3 mutants to assemble F1. Although the mutants also display lower steady-state concentrations of some F0 subunits, this could be a secondary effect of defective F1 assembly.
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PMID:Mutations in RCA1 and AFG3 inhibit F1-ATPase assembly in Saccharomyces cerevisiae. 758 36

The concentration and submitochondrial distribution of the subunit polypeptides of cytochrome oxidase have been studied in wild type yeast and in different mutants impaired in assembly of this respiratory complex. All the subunit polypeptides of the enzyme are associated with mitochondrial membranes of wild type cells, except for a small fraction of subunits 4 and 6 that is recovered in the soluble protein fraction of mitochondria. Cytochrome oxidase mutants consistently display a severe reduction in the steady-state concentration of subunit 1 due to its increased turnover. As a consequence, most of subunit 4, which normally is associated with subunit 1, is found in the soluble fraction. A similar shift from membrane-bound to soluble subunit 6 is seen in mutants blocked in expression of subunit 5a. In contrast, null mutations in COX6 coding for subunit 6 promote loss of subunit 5a. The absence of subunit 5a in the cox6 mutant is the result of proteolytic degradation rather than regulation of its expression by subunit 6. The possible role of the ATP-dependent proteases Rca1p and Afg3p in proteolysis of subunits 1 and 5a has been assessed in strains with combined mutations in COX6, RCA1, and/or AFG3. Immunochemical assays indicate that another protease(s) must be responsible for most of the proteolytic loss of these proteins.
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PMID:Submitochondrial distributions and stabilities of subunits 4, 5, and 6 of yeast cytochrome oxidase in assembly defective mutants. 927 37