Cyclic adenosine diphosphate-ribose (cADPR) plays a key role as a secondary messenger in intracellular calcium signaling. It is involved in the regulation of calcium release from intracellular stores, particularly the endoplasmic reticulum, by modulating ryanodine receptor channels. This function is critical in processes such as muscle contraction, neurotransmitter release, and hormone secretion.

cADPR is widely studied in cellular physiology for its role in immune responses, where it helps regulate T-cell activation and insulin secretion in pancreatic beta cells. It also contributes to neuronal signaling and has been linked to memory formation and synaptic plasticity in the brain.

Due to its involvement in calcium homeostasis, cADPR is a target of interest in disease research, including diabetes, neurodegenerative disorders, and cardiovascular conditions. Modulating cADPR levels or activity may offer therapeutic strategies for controlling calcium dysregulation in these diseases.