Ribonuclease MRP complex-specific subunit; ribonuclease (RNase) MRP cleaves pre-rRNA and has a role in cell cycle-regulated degradation of daughter cell-specific mRNAs; binds and assists in the folding of NME1, the RNase MRP RNA, to form the substrate-binding module; structural similarity but limited sequence homology with human RMP24 (c18orf21)