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Mitochondrial ribosomal protein S21
Symbols MRPS21 ; MRP-S21; RPMS21
External IDs OMIM611984 MGI1913542 HomoloGene45365 GeneCards: MRPS21 Gene
Species Human Mouse
Entrez 54460 66292
Ensembl ENSG00000187145 ENSMUSG00000054312
UniProt P82921 P58059
RefSeq (mRNA) NM_018997 NM_078479
RefSeq (protein) NP_061870 NP_510964
Location (UCSC) Chr 1:
150.27 – 150.28 Mb
Chr 3:
95.86 – 95.87 Mb
PubMed search [1] [2]

28S ribosomal protein S21, mitochondrial is a protein that in humans is encoded by the MRPS21 gene.[1][2]

Mammalian mitochondrial ribosomal proteins are encoded by nuclear genes and assist protein synthesis within the mitochondrion.[1] 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 28S subunit protein that belongs to the ribosomal protein S21P family.[2] Pseudogenes corresponding to this gene are found on chromosomes 1p, 1q, 9p, 10p, 10q, 16q, and 17q.[3] Available sequence data analyses identified splice variants that differ in the 5' UTR; both transcripts encode the same protein.[4]


  1. ^ a b Kenmochi N, Suzuki T, Uechi T, Magoori M, Kuniba M, Higa S, Watanabe K, Tanaka T (September 2001). "The human mitochondrial ribosomal protein genes: mapping of 54 genes to the chromosomes and implications for human disorders". Genomics 77 (1–2): 65–70. doi:10.1006/geno.2001.6622. PMID 11543634. 
  2. ^ a b Cavdar Koc E, Burkhart W, Blackburn K, Moseley A, Spremulli LL (June 2001). "The small subunit of the mammalian mitochondrial ribosome. Identification of the full complement of ribosomal proteins present". J. Biol. Chem. 276 (22): 19363–74. doi:10.1074/jbc.M100727200. PMID 11279123. 
  3. ^ Zhang Z, Gerstein M (May 2003). "Identification and characterization of over 100 mitochondrial ribosomal protein pseudogenes in the human genome". Genomics 81 (5): 468–80. doi:10.1016/S0888-7543(03)00004-1. PMID 12706105. 
  4. ^ "Entrez Gene: MRPS21 mitochondrial ribosomal protein S21". 

Further reading[edit]

Gerhard DS; Wagner L; Feingold EA et al. (2004). "The Status, Quality, and Expansion of the NIH Full-Length cDNA Project: The Mammalian Gene Collection (MGC)". Genome Res. 14 (10B): 2121–7. doi:10.1101/gr.2596504. PMC 528928. PMID 15489334.