uracil
A wobble base pair is a non-Watson Crick base pairing between two nucleotides in RNA molecules. The four main wobble base pairs are guanine-uracil, inocine-uracil, inosine-adenine, and inosine-cytosine. Wobble base pairs are fundamental in RNA secondary structure and are critical for the proper translation of the genetic code. Inosine is a nucleoside that is formed from the hydrolytic deamination of adenine. Structurally, it resembles guanine, but lacks the 2-amino group. This lack of the 2-amino group allows inosine to form base pairs with uracil, cytosine and adenine, making it a particularly wobbly base.