MITOCHONDRIAL MALIC ENZYME IN MOSAIC SKELETAL-MUSCLE OF MOUSE CHIMERAS

Whether mitochondria in the mammalian skeletal muscle fiber syncytium incorporate gene products encoded by one or many nuclei was investigated. Mouse chimeras were produced from strains which differ in their electrophoretic variants of the nuclear-coded mitochondrial protein, malic enzyme (MOD-2, EC 1.1.1.40, L-malate NADP+ oxidoreductase decarboxylating). The MOD-2 phenotypes of skeletal muscles of these chimeras were characterized in a starch gel electrophoretic system. Individual mitochondria can apparently contain products encoded by multiple nuclei and for skeletal muscle mitochondria, the cell is not subdivided into nuclear territories. Possible mechanisms of gene product distribution in skeletal muscle fibers are discussed.