Calcium Signalling
Introduction The cellular import and export pump aid in the maintenance of calcium signaling homeostasis by altering cytosolic Ca+2 concentration, which may be reversed by pumps. Calcium is imported into the cell by voltage-dependent calcium channels (VDCC), SOCC, NSCC, NCX (exchange), and NCKX (co-transport) from the extracellular side. It may also be exported out of the ER and SR via RyR controlled by IP3R to regulate the cytosolic concentration of calcium (100nM-1mM). SERCA pumps restore calcium ions into the ER and SR after voltage-gated Ca+2 channels export calcium ions out of the cell. CaN activation (PP2B), followed by NFAT dephosphorylation. Cyclosporin and voclosporin are two medicines that target CaN. Calcium Sensors and Adaptors Calmodulin (CaM) - Ubiquitous adaptor protein and specifically bind to Ca+2. ❖ Contain EF Hand domain (helix-loop-helix motif) bind to Ca. ❖ Ca bind to 7 O2 atoms (chelate Ca+2) of aa in a bipyramidal pentagonal shape. ❖ Binding with Ca induces dimer...