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mitochondrially encoded tRNA leucine 2 (CUN)
Symbol MT-TL2
Alt. symbols MTTL2
Entrez 4568
HUGO 7491
RefSeq NC_001807
Other data
Locus Chr. MT [1]

Mitochondrially encoded tRNA leucine 2 (CUN) also known as MT-TL2 is a transfer RNA which in humans is encoded by the mitochondrial MT-TL2 gene.[1]


MT-TL2 is a small 71 nucleotide RNA (human mitochondrial map position 12266-12336) that transfers the amino acid leucine to a growing polypeptide chain at the ribosome site of protein synthesis during translation.


The MT-TL2 gene is located on the p arm of the mitochondrial DNA at position 12 and it spans 75 base pairs.[2] The structure of a tRNA molecule is a distinctive folded structure which contains three hairpin loops and resembles a three-leafed clover.[3]

Clinical significance[edit]

Mutations in MT-TL2 can result in multiple mitochondrial deficiencies and associated disorders, including cardiopathy, myopathy, and encephalomyopathy. A patient with a mutation G12315A was found with encephalomyopathy with ragged-red muscle fibers.[4] A patient with a mutation of A12320G exhibited mitochondrial myopathy, and showed signs of mitochondrial myopathy.[5] In addition, multiple individuals with a T12297C substitution showed signs of cardiomyopathy accompanied with varying degrees.[6]

MT-TL2 mutations have also been associated with complex IV deficiency of the mitochondrial respiratory chain, also known as the cytochrome c oxidase deficiency. Cytochrome c oxidase deficiency is a rare genetic condition that can affect multiple parts of the body, including skeletal muscles, the heart, the brain, or the liver. Common clinical manifestations include myopathy, hypotonia, and encephalomyopathy, lactic acidosis, and hypertrophic cardiomyopathy.[7] A patient with a 12316G>A mutation in MT-TL2 was found with the deficiency.[8]


  1. ^ Anderson S, Bankier AT, Barrell BG, de Bruijn MH, Coulson AR, Drouin J, Eperon IC, Nierlich DP, Roe BA, Sanger F, Schreier PH, Smith AJ, Staden R, Young IG (April 1981). "Sequence and organization of the human mitochondrial genome". Nature. 290 (5806): 457–65. doi:10.1038/290457a0. PMID 7219534. 
  2. ^ "MT-TL2 mitochondrially encoded tRNA leucine 2 (CUN) [Homo sapiens (human)] - Gene - NCBI". 
  3. ^ "tRNA / transfer RNA". Learn Science at Scitable. 
  4. ^ Fu K, Hartlen R, Johns T, Genge A, Karpati G, Shoubridge EA (November 1996). "A novel heteroplasmic tRNAleu(CUN) mtDNA point mutation in a sporadic patient with mitochondrial encephalomyopathy segregates rapidly in skeletal muscle and suggests an approach to therapy". Human Molecular Genetics. 5 (11): 1835–40. PMID 8923013. 
  5. ^ Weber K, Wilson JN, Taylor L, Brierley E, Johnson MA, Turnbull DM, Bindoff LA (February 1997). "A new mtDNA mutation showing accumulation with time and restriction to skeletal muscle". American Journal of Human Genetics. 60 (2): 373–80. PMID 9012410. 
  6. ^ Grasso M, Diegoli M, Brega A, Campana C, Tavazzi L, Arbustini E (April 2001). "The mitochondrial DNA mutation T12297C affects a highly conserved nucleotide of tRNA(Leu(CUN)) and is associated with dilated cardiomyopathy". European Journal of Human Genetics. 9 (4): 311–5. doi:10.1038/sj.ejhg.5200622. PMID 11313776. 
  7. ^ "Cytochrome c oxidase deficiency". Genetics Home Reference.  This article incorporates text from this source, which is in the public domain.
  8. ^ Ronchi D, Virgilio R, Bordoni A, Fassone E, Sciacco M, Ciscato P, Moggio M, Govoni A, Corti S, Bresolin N, Comi GP (May 2010). "The m.12316G>A mutation in the mitochondrial tRNA Leu(CUN) gene is associated with mitochondrial myopathy and respiratory impairment". Journal of the Neurological Sciences. 292 (1-2): 107–10. doi:10.1016/j.jns.2010.01.026. PMID 20163808. 

This article incorporates text from the United States National Library of Medicine, which is in the public domain.