RNase MRP is an enzymatically active ribonucleoprotein

Ribonucleoprotein

Ribonucleoprotein is a nucleoprotein that contains RNA, i.e. it is an association that combines ribonucleic acid and protein together. A few known examples include the ribosome, the enzyme telomerase, vault ribonucleoproteins, and small nuclear RNPs , which are implicated in pre-mRNA splicing and...

 with two distinct roles in eukaryote

Eukaryote

A eukaryote is an organism whose cells contain complex structures enclosed within membranes. Eukaryotes may more formally be referred to as the taxon Eukarya or Eukaryota. The defining membrane-bound structure that sets eukaryotic cells apart from prokaryotic cells is the nucleus, or nuclear...

s. In mitochondria it plays a direct role in the initiation of mitochondrial DNA replication

D-loop replication

D-loop replication is a process by which chloroplasts and mitochondria replicate their genetic material. An important component of understanding D-loop replication is that many chloroplasts and mitochondria have a single circular chromosome like bacteria instead of the linear chromosomes found in...

. In the nucleus it is involved in precursor rRNA processing, where it cleaves

Cleavage

Cleavage may refer to:*Cleavage , partial exposure of the separation between a woman's breasts.**Cleavage enhancement, methods of making a person's breast cleavage look more substantial than it really is....

 the internal transcribed spacer 1 between 18S and 5.8S rRNAs. Despite distinct functions, RNase MRP has been shown to be evolutionarily related to RNase P

RNase P

Ribonuclease P is a type of ribonuclease which cleaves RNA. RNase P is unique from other RNases in that it is a ribozyme – a ribonucleic acid that acts as a catalyst in the same way that a protein based enzyme would. Its function is to cleave off an extra, or precursor, sequence of RNA on tRNA...

. Like eukaryotic RNase P, RNase MRP is not catalytically active without associated protein subunits.