Notes: 5-Hydroxymethylcytidine is a derivative of the pyrimidine nucleoside cytidine (Item No. 29602).{51840} It can be formed in RNA via the oxidation of 5-methylcytidine by ten-eleven translocation (TET) enzymes but can also be formed via non-TET mechanisms.{51841,51840} 5-Hydroxymethylcytidine has been found as an RNA modification in Archaea, bacteria, and eukaryotes.{51840}