From Wikipedia, the free encyclopedia
Calcium ATPase is a form of P-ATPase which transfers calcium after a muscle has contracted. The calcium ATPase are[1]:
[edit] Plasma membrane Ca2+ ATPase (PMCA)
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Rendered image of the Ca
2+ pump
The plasma membrane Ca2+ ATPase (PMCA) is a transport protein in the plasma membrane of cells that serves to remove calcium (Ca2+) from the cell. It is vital for regulating the amount of Ca2+ within cells.[2] In fact, the PMCA is involved in removing Ca2+ from all eukaryotic cells.[3] There is a very large transmembrane electrochemical gradient of Ca2+ driving the entry of the ion into cells, yet it is very important for cells to maintain low concentrations of Ca2+ for proper cell signalling; thus it is necessary for the cell to employ ion pumps to remove the Ca2+.[4] The PMCA and the sodium calcium exchanger (NCX) are together the main regulators of intracellular Ca2+ concentrations.[3] Since it transports Ca2+ into the extracellular space, the PMCA is also an important regulator of the calcium concentration in the extracellular space.[5]
The PMCA belongs to a family of P-type primary ion transport ATPases that form an aspartyl phosphate intermediate.[3]
The PMCA is expressed in a variety of tissues, including the brain.[6]
[edit] Sarcoplasmic reticulum Ca2+ ATPase (SERCA)
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SERCA resides in the sarcoplasmic reticulum (SR) within muscle cells. It is a Ca2+ ATPase which transfers Ca2+ from the cytosol of the cell to the lumen of the SR at the expense of ATP hydrolysis during muscle relaxation.
[edit] See also
[edit] References
- ^ nlm.nih.gov
- ^ Jensen, TP; Buckby LE; Empson RM (2004). "Expression of plasma membrane Ca2+ ATPase family members and associated synaptic proteins in acute and cultured organotypic hippocampal slices from rat.". Brain Research. Developmental Brain Research. 152 (2): 129–136. PMID 15351500.
- ^ a b c Strehler, EE; Zacharias DA (2001). "Role of alternative splicing in generating isoform diversity among plasma membrane calcium pumps". Physiological Reviews 81 (1): 21–50. American Physiological Society. PMID 11152753.
- ^ Carafoli, E (1991). "Calcium pump of the plasma membrane". Physiological Reviews 71 (1): 129–153. PMID 1986387.
- ^ Talarico Jr, EF; Kennedy BG; Marfurt CF; Loeffler KU; Mangini NJ (2005). "Expression and immunolocalization of plasma membrane calcium ATPase isoforms in human corneal epithelium.". Molecular Vision 11: 169–178.
- ^ Jensen, TP; Filoteo A; Knopfel T; Empson RM. (2006). "Pre-synaptic plasma membrane Ca2+ ATPase isoform 2a regulates excitatory synaptic transmission in rat hippocampal CA3". Journal of Physiology: Published online ahead of print. 17170045.
[edit] External links
