Calcium ATPase

Calcium ATPase

Calcium ATPase is a form of P-ATPase which transfers calcium after a muscle has contracted. The calcium ATPase are [ [http://www.nlm.nih.gov/cgi/mesh/2007/MB_cgi?mode=&term=Calcium+ATPase nlm.nih.gov] ] :
*Plasma membrane Ca2+ ATPase
*Sarcoplasmic reticulum Ca2+ ATPase (SERCA)

Plasma membrane Ca2+ ATPase (PMCA)

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. [ cite journal | last =Jensen | first =TP | authorlink = | coauthors = Buckby LE; Empson RM| title = Expression of plasma membrane Ca2+ ATPase family members and associated synaptic proteins in acute and cultured organotypic hippocampal slices from rat. | journal =Brain Research. Developmental Brain Research. | volume =152 | issue = 2| pages =129–136 | publisher = | date =2004 | url = | doi = | pmid = 15351500 | accessdate =2007-01-13 ] In fact, the PMCA is involved in removing Ca2+ from all eukaryotic cells.cite journal | last =Strehler | first =EE | authorlink = | coauthors =Zacharias DA | title =Role of alternative splicing in generating isoform diversity among plasma membrane calcium pumps| journal =Physiological Reviews | volume = 81| issue = 1| pages =21–50 | publisher =American Physiological Society | date =2001 | url = http://physrev.physiology.org/cgi/content/full/81/1/21?ijkey=febc5196952b9604d7293e211729df5e16861525 | doi = | pmid =11152753 | accessdate =2007-01-30 ] 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+.cite journal | last =Carafoli | first =E | authorlink = | coauthors = | title =Calcium pump of the plasma membrane | journal =Physiological Reviews | volume =71 | issue =1 | pages =129–153 | publisher = | date =1991 | url =http://physrev.physiology.org/cgi/reprint/71/1/129?ijkey=07dce5327b657cc65fb6152751c728391912b332&keytype2=tf_ipsecsha| doi = | pmid =1986387 | accessdate =2007-01-30 ] The PMCA and the sodium calcium exchanger (NCX) are together the main regulators of intracellular Ca2+ concentrations.Since it transports Ca2+ into the extracellular space, the PMCA is also an important regulator of the calcium concentration in the extracellular space. cite journal | last =Talarico Jr | first =EF | authorlink = | coauthors =Kennedy BG; Marfurt CF; Loeffler KU; Mangini NJ | title = Expression and immunolocalization of plasma membrane calcium ATPase isoforms in human corneal epithelium.| journal =Molecular Vision | volume =11 | issue = | pages = 169–178| publisher = | date =2005 | url =http://www.molvis.org/molvis/v11/a19/ | doi = | id = | accessdate = ]

The PMCA belongs to a family of P-type primary ion transport ATPases that form an aspartyl phosphate intermediate.

The PMCA is expressed in a variety of tissues, including the brain. cite journal | last =Jensen | first =TP | authorlink = | coauthors =Filoteo A; Knopfel T; Empson RM. | title =Pre-synaptic plasma membrane Ca2+ ATPase isoform 2a regulates excitatory synaptic transmission in rat hippocampal CA3 | journal =Journal of Physiology | volume = | issue = | pages =Published online ahead of print | publisher = | date =2006 | url =http://jp.physoc.org/cgi/rapidpdf/jphysiol.2006.123901v1| doi = | id =17170045 | accessdate =2007-01-13 ]

Sarcoplasmic reticulum Ca2+ ATPase (SERCA)

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.

See also

* Active transport#Counter-transport

References

External links

*
*
* [http://www.utoronto.ca/maclennan/rint1.htm Overview at utoronto.ca]
* [http://www.sanger.ac.uk//cgi-bin/Pfam/getacc?PF00689 Cation transporting ATPase family in Pfam]
* - Calculated orientations of calcium ATPase in membrane


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