Abstract 9405363 The enzyme complexes of the mitochondrial electron transport chain are unique. Each complex is composed of subunits encoded in two different genomes, the mitochondrial and the nuclear genomes. Cytochrome c oxidase (COX), the last enzyme complex in the chain provides an ideal model system in which to analyze both coordinate and tissue-specific transcriptional regulation of these essential respiratory genes. The long-term goal of this project is to understand the genetic regulatory mechanisms controlling both tissue-specific expression and developmental regulation of mammalian genes for the mitochondrial-encoded COX subunits. We will (1) define skeletal muscle-specific enhancer elements in the gene for COX subunit VIII-H by means of gene fusions with either the CAT or lacZ reporter genes (2) map the sites of DNA-protein interactions between nuclear proteins and tissue-specific enhancers in the COX8H gene by DNAse hypersensitivity, DNAse footprinting and electrophoretic mobility shift assays and determine the functional significance of these interactions by gene transactivation studies (3) physically map the bovine genes for the tissue-specific isoforms of COX subunit VIII and (4) nap the COX VIII isoform genes in the mouse by inter-specific hybrid back-crosses. %%% These studies will constitute the first comprehensive analysis of the transcriptional regulation of a class of genes, the tissue- specific respiratory genes, essential for respiratory function in contractile muscle. The results should provide insight into the genetic regulation of tissue-specific subunits of an essential multi-subunit enzyme complex involved in oxidative metabolism and provide tools to enable us to address the function of these isoforms in future studies. ***
