SERCA 697026 177162297 2007-12-11T06:31:08Z Biophys 2497317 '''SERCA''' stands for [[sarcoplasmic reticulum|Sarco]]/[[endoplasmic reticulum|Endoplasmic Reticulum]] [[Calcium|Ca]]<sup>2+</sup>-[[ATPase]]. It is a [[P-ATPase#P-ATPase|P-ATPase]] of the [[calcium ATPase]] type. ==Function== SERCA resides in the [[sarcoplasmic reticulum]] (SR) within [[muscle cell]]s. It is a Ca<sup>2+</sup> ATPase which transfers Ca<sup>2+</sup> from the [[cytosol]] of the cell to the [[lumen]] of the SR at the expense of [[ATP hydrolysis]] during muscle relaxation. ==Regulation== SERCA is normally somewhat inhibited by a protein, [[phospholamban]], with which it is closely associated. Another protein, [[calsequestrin]], binds calcium within the SR and helps to reduce the concentration of free calcium within the SR, which assists SERCA so that it does not have to pump against such a high concentration gradient. The SR has a much higher concentration of Ca<sup>2+</sup> (10,000x) inside when compared to the intracellular Ca<sup>2+</sup> concentration. The rate at which SERCA moves Ca<sup>2+</sup> across the SR membrane can be controlled by [[phospholamban]] (PLB/PLN) under [[β-adrenergic]] stimulation. When PLB is associated with SERCA, the rate of Ca<sup>2+</sup> movement is reduced, upon dissociation of PLB Ca<sup>2+</sup> movement increases. ==Paralogs== There are 3 major [[paralogs]], SERCA1-3, which are expressed at various levels in different cell types. * {{Gene|ATP2A1}} - SERCA1 * {{Gene|ATP2A2}} - SERCA2 * {{Gene|ATP2A3}} - SERCA3 There are additional post-translational isoforms of both SERCA2 and 3 which serve to introduce the possibility of cell type specific Ca<sup>2+</sup>-reuptake responses as well as increasing the overall complexity of the Ca<sup>2+</sup> signalling mechanism. ==External links== * {{MeshName|Sarcoplasmic+Reticulum+Calcium-Transporting+ATPases}} {{biochem-stub}} {{Ion pumps}} [[Category:Microbiology]] [[Category:Transmembrane proteins]]