RNASE MITOCHONDRIAL RNA PROCESSING CLEAVES RNA FROM THE RAT MITOCHONDRIAL DISPLACEMENT LOOP AT THE ORIGIN OF HEAVY-STRAND DNA-REPLICATION

Ribonuclease mitochondrial RNA processing cleaves RNAs from the mammal ian mitochondrial main non-coding regulatory region, called the displa cement loop. Our data demonstrate that rat cells contain a site-specif ic ribonuclease mitochondrial RNA processing activity. We found that t his enzyme processes the rat mitochondrial displacement-loop RNA subst rate at the level of the conserved sequence block 1, a result which is different from that for mouse. This finding correlates with the in-vi vo transcriptional analysis of the rat displacement-loop region. Proce ssing by homologous and heterologous ribonuclease mitochondrial RNA en zymes occurs in the same manner, suggesting a conserved mode of substr ate recognition.