Cyclic Nucleotides

Cyclic nucleotides are purine derivative compounds that have a key role as second messengers in the mechanism of action of externally signaling agents including hormones, growth factors, regulatory peptides, and neurotransmitters. Two cyclic nucleotides, cyclic adenosine 3’,5’-monophosphate (cyclic AMP or cAMP) and cyclic guanine 3’5’-monophosphate (cyclic GMP or cGMP), are involved in such functions, but the first of them, cAMP, is considered to be the most important cyclic nucleotide second messenger in mammalian cells. ^1-6 The possible role of a third cyclic nucleotide, cyclic cytidine 3’,5’-monophosphate (cCMP), in the regulation of cellular functions by external stimuli is controversial. ⁷