The proposed work will result in the characterization of the bovine nuclear gene that specifies subunit IV of the mitochondrial cytochrome oxidase (COX IV). Bachman's previous work led to the isolation of a cDNA corresponding to the COX IV mRNA. This will be used in a straightforward way to isolate genomic clones. She has evidence for at least two genes, one of which appears to be a pseudogene. Using these clones, it should be possible to develop gene-specific probes which Bachman will then use to study a variety of aspects of the regulation of the gene(s). The cytochrome oxidase (COX) of the mitochondrion is a large complex of different proteins, three of which are encoded by the mitochondrial DNA while the remainder are specified by the nuclear genome. The number of such nuclear subunits varies: in yeast there are 5; in mammals, about 10. Several interesting regulatory problems are presented by this enzyme. These include the mechanism that coordinates expression of the nuclear and mitochondrial genes, and the mechanism, possibly the same, that regulates expression in different tissues. As yet, virtually nothing is known about the structure and regulation of these nuclear genes in mammals. The work proposed by Dr. Bachman will lead to the isolation and characterization of gene(s) for the largest of the mammalian nuclear subunits, COX IV, and should provide some insight into the mechanisms which regulate its expression.
