| Criteria | Cyclic Adenosine Monophosphate (cAMP) | Adenosine Monophosphate (AMP) | Remarks |
| Chemical Structure | Contains a cyclic phosphate bond between the 3′ and 5′ hydroxyl of ribose | Contains a linear phosphate attached to the 5′ hydroxyl of ribose | cAMP has a ring structure, whereas AMP has a linear phosphate group |
| Molecular Formula | C10H12N5O6P (cyclic form) | C10H14N5O7P (linear form) | cAMP is a derivative of AMP formed via cyclization of the phosphate group |
| Formation | Synthesized from ATP by adenylate cyclase in response to signaling cues | Formed during ATP hydrolysis or RNA degradation | cAMP is produced as a secondary messenger, AMP often as a metabolic intermediate |
| Function | Functions as a second messenger in signal transduction | Functions in nucleotide metabolism and RNA structure | cAMP has regulatory roles, while AMP serves structural and metabolic functions |
| Role in Signaling | Activates protein kinase A (PKA), regulates gene expression | Precursor or by-product; not typically a signaling molecule | cAMP is key in many hormone response pathways |
| Enzymatic Degradation | Broken down by phosphodiesterases to AMP | Can be phosphorylated to ADP or ATP or incorporated into RNA | Conversion of cAMP to AMP terminates signaling |
| Biological Role | Signal transduction, cell regulation, response to hormones | Building block of RNA, energy metabolism | They operate in distinct cellular pathways |
| Cellular Concentration | Maintained at low levels; rapidly increases upon stimulation | Generally present in higher basal levels | Tight regulation of cAMP levels is essential for precise signal modulation |
| Stability | Less stable due to susceptibility to phosphodiesterase action | More stable; accumulates under metabolic stress | AMP is more persistent, whereas cAMP is transient |
| Presence in RNA | Not a component of RNA | Directly incorporated into RNA during transcription | AMP is one of the four canonical RNA nucleotides |
