Ca2regulated

Ca2-regulated refers to biological processes, proteins, or pathways whose activity is controlled by intracellular calcium ions (Ca2+). Calcium serves as a universal second messenger in many cells and tissues, translating stimuli into diverse responses such as muscle contraction, neurotransmitter release, secretion, and gene expression.

Most Ca2+-regulated actions depend on Ca2+-binding proteins, particularly those with EF-hand motifs such as calmodulin, troponin C, and various S100 proteins. Binding of Ca2+ induces conformational changes that enable interactions with target enzymes, receptors, or structural proteins, thereby modulating activity.

Examples include calmodulin-dependent kinases (CaMKs) and calcineurin, which regulate downstream enzymes and transcription factors; troponin C mediating skeletal and cardiac muscle contraction; and synaptotagmin acting as a Ca2+ sensor to trigger neurotransmitter release. Calcium can also regulate enzymes directly or via calmodulin-dependent pathways.

Calcium homeostasis is maintained by channels, pumps, and exchangers that control cytosolic Ca2+ levels. Influx occurs through voltage-gated calcium channels; release from internal stores occurs via IP3 receptors and ryanodine receptors; removal of cytosolic Ca2+ is achieved by pumps such as PMCA and SERCA and by exchangers such as NCX. Ca2+ buffers and binding proteins shape transients.

Disruptions of Ca2+-regulated signaling are linked to several conditions, including cardiac arrhythmias, neurodegenerative diseases, and metabolic disorders. Researchers study Ca2+ dynamics with indicators such as Fura-2, Fluo-4, and genetically encoded GCaMP probes, and with pharmacological tools including calcium channel blockers and calmodulin modulators.

Overall, Ca2+-regulated processes are central to cellular signaling, linking electrical or hormonal stimuli to diverse cellular outcomes.