adenylate

Adenylate is a term used in biochemistry to refer to the adenosine monophosphate (AMP) moiety, the nucleotide consisting of adenine attached to a ribose sugar and a single phosphate group. In broader usage, it can denote adenosine-containing nucleotides or their phosphate groups, including ADP and ATP, particularly when discussing energy metabolism or phosphorylation states.

In metabolism, adenylates serve as central energy currencies. ATP stores and donates energy in countless cellular reactions; ADP and AMP are formed when ATP is hydrolyzed and are themselves substrates for rephosphorylation. The interconversion among ATP, ADP, and AMP is mediated by enzymes such as adenylate kinase, and the cellular energy status is often described by the adenylate energy charge, a ratio involving ATP, ADP, and AMP that helps regulate metabolic pathways.

Adenylates also participate in signaling. The enzyme adenylate cyclase converts ATP into cyclic AMP (cAMP), a key second messenger that activates protein kinase A and coordinates responses to hormones and other stimuli, influencing processes from metabolism to gene expression.

Biosynthesis and turnover involve both de novo purine synthesis and salvage pathways. AMP can be formed from inosine monophosphate (IMP) or from adenosine through phosphorylation; the three adenylate nucleotides are interconverted by kinases and nucleotidases. Catabolic pathways release adenosine, which is recycled or further degraded.

The term adenylation (AMPylation) also describes the covalent attachment of an AMP moiety to proteins or other targets, a regulatory post-translational modification observed in various organisms and contexts.