3-Methylcytidine (methosulfate) is a cytidine derivative used as an internal standard for HPLC. 3-Methylcytidine is a common epigenetic modification in tRNA but its role in the cell has not been defined.[1] 3-Methylcytidine has been investigated as a potential biomarker for cancer and was significantly elevated in the urine of breast cancer patients.[2]
Reference:
[1]. D'Silva, S., Haider, S.J., and Phizicky, E.M. A domain of the actin binding protein Abp140 is the yeast methyltransferase responsible for 3-methylcytidine modification in the tRNA anti-codon loop. RNA 17(6), 1100-1110 (2011).
[2]. Hsu, W.Y., Chen, C.J., Huang, Y.C., et al. Urinary nucleosides as biomarkers of breast, colon, lung, and gastric cancer in Taiwanese. PLoS One 8(12), 1-8 (2013).