MRP-L39 (mitochondrial ribosomal protein L39), also known as MRP-L5, L39mt or L5mt, is a 338 amino acid mitochondrial protein that exists as a component of the 39S ribosomal subunit and works in conjunction with other MRPs to mediate protein synthesis. MRP-L39 exists as two isoforms produced by alternative splicing. Isoform one of MRP-L39 is ubiquitously expressed while isoform two is specifically expressed in heart. The gene encoding MRP-L39 maps to chromosome 21, which makes up about 1.5% of the human genome. Chromosome 21 contains nearly 300 genes and 47 million base pairs. Down syndrome, also known as trisomy 21, is the disease most commonly associated with chromosome 21.
