CHARACTERIZATION AND EXPRESSION OF THE MOUSE ENDONUCLEASE-G GENE

Endonuclease G (Endo G) is a nuclease of prokaryotic lineage found in the mitochondria of vertebrates that has been suggested to play a role in mitochondrial DNA (mtDNA) replication, We have isolated and sequen ced the entire mouse endo G gene, determined the limits of the mRNA, a nd mapped the promoter region, The coding sequence of the single copy gene is interrupted by two introns and analysis of the transcripts doe s not support a model by which more than one Endo G isoform could be p roduced by alternative splicing. We have also characterized a full-len gth human Endo G cDNA and comparison at the protein level of the human , bovine, and murine nucleases indicates a high degree of conservation except in the respective mitochondrial targeting signals, Endo G is u biquitously expressed and the steady-state levels of its mRNA vary by a factor greater than seven between different tissues, The relationshi p between the mtDNA copy number and Endo G mRNA levels is not strictly proportional but tissues richer in mtDNA have higher amounts of the m RNA and vice versa.