{"symbol":"MRPL21","synonyms":["L21MT","MRP-L21"],"name":"mitochondrial ribosomal protein L21","description":"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. They have an estimated 75% protein to rRNA composition compared to prokaryotic ribosomes, where this ratio is reversed. Another difference between mammalian mitoribosomes and prokaryotic ribosomes is that the latter contain a 5S rRNA. Among different species, the proteins comprising the mitoribosome differ greatly in sequence, and sometimes in biochemical properties, which prevents easy recognition by sequence homology. This gene 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). [provided by RefSeq, Jul 2008]","ncbiEntrezGeneId":219927,"ncbiEntrezGeneUrl":"http://www.ncbi.nlm.nih.gov/gene/219927","proteins":[{"symbol":"RM21_HUMAN","href":"/api/1.0/protein/RM21_HUMAN"}],"hgncRootFamilies":[{"name":"Mitochondrial ribosomal proteins (MRPL, MRPS)","href":"/api/1.0/gene_family/Mitochondrial+ribosomal+proteins+%28MRPL%2C+MRPS%29"}]}