Skeletal formula of 5-methyluridine
Space-filling model of the 5-methyluridine molecule
IUPAC name
Systematic IUPAC name
Other names
Ribothymidine, Ribosylthymine; Thymine riboside, m5U
3D model (JSmol)
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  • InChI=1S/C10H14N2O6/c1-4-2-12(10(17)11-8(4)16)9-7(15)6(14)5(3-13)18-9/h2,5-7,9,13-15H,3H2,1H3,(H,11,16,17)/t5-,6-,7-,9-/m1/s1 ☒N
  • InChI=1/C10H14N2O6/c1-4-2-12(10(17)11-8(4)16)9-7(15)6(14)5(3-13)18-9/h2,5-7,9,13-15H,3H2,1H3,(H,11,16,17)/t5-,6-,7-,9-/m1/s1
  • CC1=CN(C(=O)NC1=O)[C@H]2[C@@H]([C@@H]([C@H](O2)CO)O)O
Molar mass 258.23 g/mol
Density 1,6 g/cm3[1]
Melting point 184[2] °C (363 °F; 457 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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The chemical compound 5-methyluridine (symbol m5U or m5U), also called ribothymidine (rT)[footnote 1], is a pyrimidine nucleoside. It is the ribonucleoside counterpart to the deoxyribonucleoside thymidine, which lacks a hydroxyl group at the 2' position. 5-Methyluridine contains a thymine base joined to a ribose pentose sugar.[4] It is a white solid.

m5U is one of the most common modifications made to cellular RNA. It almost universally occurs in position 54 (part of the T arm) of eukaryotic and bacterial tRNA, serving to stabilize the molecule. The same "T-loop" motif occurs in many other forms of noncoding RNA such as tmRNA and rRNA. Loss of the tRNA modification does not usually produce a different, less fit, phenotype.[5]

See also


  1. ^ The term ribothymidine is especially used to describe its unusual occurrence in RNA.[3]


  1. ^ "5-Methyluridine". ChemSpider. Retrieved December 6, 2018.
  2. ^ William M. Haynes (2016). CRC Handbook of Chemistry and Physics (97th ed.). Boca Raton: CRC Press. p. 3-400. ISBN 978-1-4987-5429-3.
  3. ^ Lehninger Principles of Biochemistry (6th ed.). W. H. Freeman and Company. 2013. p. 282. ISBN 9781429234146.
  4. ^ Shobbir Hussain (2019). "Catalytic crosslinking-based methods for enzyme-specified profiling of RNAribonucleotide modifications". Methods. 156: 60–65. doi:10.1016/j.ymeth.2018.10.003. PMID 30308313. S2CID 52961265.
  5. ^ Powell, CA; Minczuk, M (April 2020). "TRMT2B is responsible for both tRNA and rRNA m(5)U-methylation in human mitochondria". RNA Biology. 17 (4): 451–462. doi:10.1080/15476286.2020.1712544. PMC 7237155. PMID 31948311.