Page "RNA" Paragraph 18

RNA is transcribed with only four bases ( adenine, cytosine, guanine and uracil ), but these bases and attached sugars can be modified in numerous ways as the RNAs mature.

Pseudouridine ( Ψ ), in which the linkage between uracil and ribose is changed from a C – N bond to a C – C bond, and ribothymidine ( T ) are found in various places ( the most notable ones being in the TΨC loop of tRNA ).

Another notable modified base is hypoxanthine, a deaminated adenine base whose nucleoside is called inosine ( I ).

Inosine plays a key role in the wobble hypothesis of the genetic code.