RNASE MRP AND RNASE-P SHARE A COMMON SUBSTRATE

RNase MRP is a site-specific ribonucleoprotein endoribonuclease that p rocesses RNA from the mammalian mitochondrial displacement loop contai ning region. RNase P is a site-specific ribonucleoprotein endoribonucl ease that processes pre-tRNAs to generate their mature 5'-ends. A simi lar structure for the RNase P and RNase MRP RNAs and a common cleavage mechanism for RNase MRP and RNase P enzymes have been proposed. Exper iments with protein synthesis antibiotics have shown that both RNase M RP and RNase P are inhibited by puromycin. We also show that E.coli RN ase P cleaves the RNase MRP substrate, mouse mitochondrial primer RNA, exactly at a site that is cleaved by RNase MRP.