Mitochondrially encoded tRNA tyrosine, also known as MT-TY, is a

transfer RNA Transfer RNA (abbreviated tRNA and formerly referred to as sRNA, for soluble RNA) is an adaptor molecule composed of RNA, typically 76 to 90 nucleotides in length (in eukaryotes), that serves as the physical link between the mRNA and the amino ac ...

which in humans is encoded by the

mitochondrial A mitochondrion (; ) is an organelle found in the cells of most Eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is use ...

''MT-TY'' gene.

Structure

The ''MT-TY'' gene is located on the p arm of the non-nuclear

mitochondrial DNA Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial D ...

at position 12 and it spans 66 base pairs. The structure of a tRNA molecule is a distinctive folded structure which contains three hairpin loops and resembles a three-leafed clover.

Function

MT-TY is a small 66 nucleotide

RNA Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA and deoxyribonucleic acid ( DNA) are nucleic acids. Along with lipids, proteins, and carbohydra ...

(human mitochondrial map position 5826-5891) that transfers the amino acid tyrosine to a growing

polypeptide Peptides (, ) are short chains of amino acids linked by peptide bonds. Long chains of amino acids are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides. A p ...

chain at the

ribosome Ribosomes ( ) are macromolecular machines, found within all cells, that perform biological protein synthesis (mRNA translation). Ribosomes link amino acids together in the order specified by the codons of messenger RNA (mRNA) molecules to ...

site of protein synthesis during translation.

Clinical significance

Mutations in ''MT-TY'' have been associated with mitochondrial complex III deficiency, a genetic condition that can affect several parts of the body, including the brain, kidneys, liver, heart, and the skeletal muscles. Common clinical manifestations include muscle weakness (

myopathy In medicine, myopathy is a disease of the muscle in which the muscle fibers do not function properly. This results in muscular weakness. ''Myopathy'' means muscle disease (Greek : myo- ''muscle'' + patheia '' -pathy'' : ''suffering''). This meani ...

) and extreme tiredness (

fatigue Fatigue describes a state of tiredness that does not resolve with rest or sleep. In general usage, fatigue is synonymous with extreme tiredness or exhaustion that normally follows prolonged physical or mental activity. When it does not resolve ...

), particularly during exercise ( exercise intolerance). Additional symptoms may also arise depending on the severity of the condition. A patient with a mutation of the gene exhibited complex III deficiency, characterized by high levels of cytochrome c oxidase–deficient fibers with symptoms of weakness and fatigue. A 5874A-G mutation was also found in a patient with the condition. Changes in ''MT-TY'' may also result in progressive external ophthalmoplegia. Progressive external ophthalmoplegia is characterized by weakness of the eye muscles. Common symptoms of the disorder include hearing loss, loss of sensation in the limbs, ataxia, and

neuropathy Peripheral neuropathy, often shortened to neuropathy, is a general term describing disease affecting the peripheral nerves, meaning nerves beyond the brain and spinal cord. Damage to peripheral nerves may impair sensation, movement, gland, or o ...

. A 5885T deletion and 5877G-A substitution have been associated with the disease.

References

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