Adenosine 5-monophosphate monohydrate (5-AMP) , also known as 5-adenylic acid, is a nucleotide that is used as a monomer in RNA. It is an ester of phosphoric acid and the nucleoside adenosine. Adenosine 5-monophosphate monohydrate consists of a phosphate group, the sugar ribose, and the nucleobase adenine. As a substituent it takes the form of the prefix adenylyl-.