Assignment of the human mitochondrial translational release factor 1 (MTRF1) to chromosome 13q14.1-->q14.3 and of the human mitochondrial ribosome recycling factor (MRRF) to chromosome 9q32-->q34.1 with radiation hybrid mapping.

The human mitochondrial genome is transcribed and translated by gene products encoded by the nuclear genome. The termination of peptide chain synthesis in mitochondria is controlled by release factor 1 (mRF1) which is supposed to read the stop codon. Errors in termination due to a defect or missing mRF1 might lead to carboxy-terminal extensions of the mitochondrial encoded proteins with consequences for energy metabolism and apoptosis via cytochrome C. The release factor has been identified and partly characterized (Zhang and Spremulli, 1998) (LocusLink 9617) as highly homologous to the bacterial release factor 1 (RF1) and less homologous to the cytoplasmic RF1 (ETF1, LocusLink 2107). The ribosome recycling factor is a nuclear encoded mitochondrial protein, which is necessary for recycling of ribosomes after the termination of a peptide chain catalyzed by the mitochondrial translational release factor 1 (MTRF1). The factor is a GTP binding protein with high homology to the bacterial RRF (Zhang and Spremulli, 1998) (LocusLink 10304). There is no known cytoplasmic homologue to mRRF. Materials and methods