Mitochondrial Ribosomal Protein L21 (MRPL21)

Mammalian mitochondrial ribosomal proteins are encoded by nuclear genes and help in protein synthesis within the mitochondrion. Mitochondrial ribosomes (mitoribosomes) consist of a small 28S subunit and a large 39S subunit. Among different species, the proteins comprising the mitoribosome differ greatly in sequence, and sometimes in biochemical properties, which prevents easy recognition by sequence homology. MRPL21 encodes a 39S subunit protein. Multiple transcript variants encoding different isoforms were identified through sequence analysis although some may be subject to nonsense-mediated decay (NMD). deduced 205-amino acid protein has an N-terminal mitochondrial import signal. MRPL21 homologs in all species examined, including plants. Mouse and human MRPL21 share 80% amino acid identity.