Calcium ATPase - Misplaced Pages

Plasma membrane Ca ATPase (PMCA) is a transport protein in the plasma membrane of cells that serves to remove calcium (Ca) from the cell. It is vital for regulating the amount of Ca within cells. In fact, the PMCA is involved in removing Ca from all eukaryotic cells. There is a very large transmembrane electrochemical gradient of Ca driving the entry of the ion into cells, yet it is very important for cells to maintain low concentrations of Ca for proper cell signalling; thus it is necessary for the cell to employ ion pumps to remove the Ca. The PMCA and the sodium calcium exchanger (NCX) are together the main regulators of intracellular Ca concentrations. Since it transports Ca into the extracellular space, the PMCA is also an important regulator of the calcium concentration in the extracellular space.

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.

Sarcoendoplasmic Reticulum Ca ATPase (SERCA)

Main article: SERCA

In myocytes (muscle cells) Ca is normally sequestered (isolated) in a specialized form of endoplasmic reticulum (ER) called sarcoplasmic reticulum (SR). It is a Ca ATPase that transfers Ca from the cytosol of the cell to the lumen of the SR at the expense of ATP hydrolysis during muscle relaxation. In the skeletal muscles the calcium pump in the sarcoplasmic reticulum membrane works in harmony with similar calcium pumps in the plasma membrane. This ensures that the cytosolic concentration of free calcium in resting muscle is below 0.1 μM. The sarcoplasmic and endoplasmic reticulum calcium pumps are closely related in structure and mechanism, and both are inhibited by the tumor-promoting agent thapsigargin, which does not affect the plasma membrane Ca pumps.

References

PDB Molecule of the Month Calcium pump
nlm.nih.gov
Jensen TP, Buckby LE, Empson RM (September 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): 129–36. doi:10.1016/j.devbrainres.2004.06.004. PMID 15351500.
^ Strehler EE, Zacharias DA (January 2001). "Role of alternative splicing in generating isoform diversity among plasma membrane calcium pumps". Physiological Reviews. 81 (1). American Physiological Society: 21–50. doi:10.1152/physrev.2001.81.1.21. PMID 11152753.
Carafoli E (January 1991). "Calcium pump of the plasma membrane". Physiological Reviews. 71 (1): 129–53. doi:10.1152/physrev.1991.71.1.129. PMID 1986387.
Talarico EF, Kennedy BG, Marfurt CF, Loeffler KU, Mangini NJ (March 2005). "Expression and immunolocalization of plasma membrane calcium ATPase isoforms in human corneal epithelium". Molecular Vision. 11: 169–78. PMID 15765049.
Jensen TP, Filoteo AG, Knopfel T, Empson RM (February 2007). "Presynaptic plasma membrane Ca2+ ATPase isoform 2a regulates excitatory synaptic transmission in rat hippocampal CA3". The Journal of Physiology. 579 (Pt 1): 85–99. doi:10.1113/jphysiol.2006.123901. PMC 2075377. PMID 17170045. 17170045. Archived from the original on September 27, 2007.

External links

Calcium+ATPase at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
EC 7.2.2.10
Overview at utoronto.ca
Cation transporting ATPase family in Pfam

Membrane transport protein: ion pumps, ATPases / ATP synthase (TC 3A2-3A3)

F-, V-, and A-type ATPase (3.A.2)

H (F-type)

H (V-type)

TCIRG1

A-ATPase

found in Archea

P-type ATPase (3.A.3)

3.A.3.1.4: H/K transporting, nongastric: ATP12A

3.A.3.2: Ca (SERCA, PMCA, SPCA) / Ca transporting: ATP2A1
ATP2A2
ATP2A3
ATP2B1
ATP2B2
ATP2B3
ATP2B4
ATP2C1

3.A.3.5: Cu transporting: ATP7A
ATP7B

3.A.3.8.8: flippase: ATP8A2

Other/ungrouped:

Na/K – H

Mg transporting: ATP3
Class I, type 8: ATP8A1
ATP8B1
ATP8B2
ATP8B3
ATP8B4
Class II, type 9: ATP9A
ATP9B
Class V, type 10: ATP10A
ATP10B
ATP10D
Class VI, type 11: ATP11A
ATP11B
ATP11C
type 13: ATP13A1
ATP13A2
ATP13A3
ATP13A4
ATP13A5

see also ATPase disorders

Hydrolases: acid anhydride hydrolases (EC 3.6)

3.6.1

3.6.2

3.6.3-4: ATPase

3.6.3

Cu++ (3.6.3.4)	Menkes/ATP7A Wilson/ATP7B
Ca+ (3.6.3.8)	SERCA ATP2A1 ATP2A2 ATP2A3 Plasma membrane ATP2B1 ATP2B2 ATP2B3 ATP2B4 SPCA ATP2C1 ATP2C2
Na+/K+ (3.6.3.9)	ATP1A1 ATP1A2 ATP1A3 ATP1A4 ATP1B1 ATP1B2 ATP1B3 ATP1B4
H+/K+ (3.6.3.10)	ATP4A
Other P-type ATPase	ATP8B1 ATP10A ATP11B ATP12A ATP13A2 ATP13A3

3.6.4

3.6.5: GTPase

3.6.5.1: Heterotrimeric G protein	G_αs G_olf G_αi GNAI1 GNAI2 GNAI3 Transducin GNAT1 GNAT2 Gustducin GNAT3 G_αq/11 GNAQ GNA11 G_α12/13 GNA12 GNA13
3.6.5.2: Small GTPase > Ras superfamily	Rho family of GTPases: Cdc42 CDC42 TC10 TCL RhoUV RhoU RhoV Rac Rac1 2 3 RhoG RhoBTB 1 2 RhoH Rho A B C Rnd 1 2 3 RhoDF RhoF RhoD other: Ras HRAS KRAS NRAS Rab RAB23 RAB27 Arf ARF6 SAR1B ARL13B ARL6 Ran Rheb Rap RGK
3.6.5.3: Protein-synthesizing GTPase	Prokaryotic IF-2 EF-Tu EF-G Eukaryotic
3.6.5.5-6: Polymerization motors	dynamin superfamily Dynamin Guanylate-binding protein Mitofusin-1 MX1 and MX2 OPA1 Tubulin

v t e Enzymes
Activity	Active site Binding site Catalytic triad Oxyanion hole Enzyme promiscuity Diffusion-limited enzyme Cofactor Enzyme catalysis
Regulation	Allosteric regulation Cooperativity Enzyme inhibitor Enzyme activator
Classification	EC number Enzyme superfamily Enzyme family List of enzymes
Kinetics	Enzyme kinetics Eadie–Hofstee diagram Hanes–Woolf plot Lineweaver–Burk plot Michaelis–Menten kinetics
Types	EC1 Oxidoreductases (list) EC2 Transferases (list) EC3 Hydrolases (list) EC4 Lyases (list) EC5 Isomerases (list) EC6 Ligases (list) EC7 Translocases (list)

Portal:

Biology

Categories:

Plasma membrane Ca ATPase (PMCA)

Sarcoendoplasmic Reticulum Ca ATPase (SERCA)

See also

References

External links