Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Uridine monophosphate, also known as 5'-uridylic acid and abbreviated UMP, is a nucleotide that is used as a monomer in RNA. It is an ester of phosphoric acid with the nucleoside uridine. UMP consists of the phosphate group, the pentose sugar ribose, and the nucleobase uracil; hence, it is a ribonucleoside monophosphate. Another common shorthand for the molecule is uridylate - the deprotonated form of the molecule, which is predominant in aqueous solution. As a substituent it takes the form of the prefix uridylyl-.