calciumkanavans

Calciumkanavans are membrane proteins that selectively permit calcium ions (Ca2+) to cross cellular membranes in response to specific stimuli. They translate electrical, chemical, or mechanical signals into intracellular calcium signals, which regulate processes such as muscle contraction, neurotransmitter release, gene expression, and enzyme activity. Calciumkanavans are found in the plasma membranes of neurons, cardiac and smooth muscle cells, pancreatic beta cells, and many other cell types, as well as in organellar membranes where relevant.

Most studied calciumkanavans are voltage-gated channels (VGCCs), composed around a pore-forming alpha1 subunit and auxiliary subunits. They are organized into major groups: Cav1 (L-type), Cav2 (P/Q-, N-, and R-type), and Cav3 (T-type). Other calcium-permeable channels include ligand-gated or receptor-operated channels (examples include NMDA receptors) and store-operated channels such as Orai1 activated by depletion of endoplasmic reticulum Ca2+ through STIM proteins.

Activation and regulation of calciumkanavans depend on the channel type. VGCCs open in response to membrane depolarization, while ligand-gated channels respond to transmitter or hormone binding. Intracellular calcium itself can modulate channels via calcium-dependent inactivation and signaling pathways. Phosphorylation by kinases such as PKA, PKC, or CaMKII further tunes channel activity, enabling integration into broader cellular signaling networks.

Physiological roles of calciumkanavans include triggering vesicle fusion and neurotransmitter release, initiating cardiac and smooth muscle contraction, and influencing secretion, metabolism, and gene expression. They are targets of pharmacological drugs and genetic mutations.

Clinical relevance includes the use of calcium channel blockers to treat hypertension and angina, as well as associations between calcium channel gene mutations and channelopathies and neurodevelopmental disorders.