Sandbox Reserved 970: Difference between revisions

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== Introduction ==

All living organisms depend on P-type ATPase to pump cation across the membrane. They play a fundamental role in their metabolism and physiology. Ca2+ ATPase, a P-type ATPase, transports calcium ions across the membrane against a concentration gradient. These pumps clear cytoplasm of the second messenger, the calcium. It's very important to keep a low concentration of calcium in the cell for a good cell signaling.

All living organisms depend on P-type ATPase to pump cation across the membrane. They play a fundamental role in their metabolism and physiology. Ca2+ ATPase, a P-type ATPase, transports calcium ions across the membrane against a concentration gradient. These pumps clear cytoplasm of the second messenger, the calcium. It's very important to keep a low concentration of calcium in the cell for a good cell signaling.The hydrolysis of one adenosine triphosphate (ATP) is essential for the functioning of the pump and the transport of one calcium ion.

We can found the PMCA (Plasma Membrane Ca2+ ATPase) which remove the calcium from the cell and the SERCA (Sarcoplasmic Endoplasmic Reticulum Ca2+ ATPase) which pumps calcium into the endoplasmic reticulum.

The hydrolysis of one adenosine triphosphate (ATP) is essential for the functioning of the pump and the transport of one calcium ion.

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The architecture of calcium ATPase (determined by X-Ray crystallography) allow to understand mechanisms by which the energy of ATP is coupled to the calcium transport across a membrane.

'''The first step of the calcium pump catalytic cycle is the cooperative binding of two calcium ions in the calcium binding cavity. Then, ATP binds to the ATP binding site (nucleotide binding domain) and transfers its γ-phosphate to the aspartic acide 351 (phosphorylation domain). That creates a acid-stable aspartyl phosphate intermediate. The phosphorylation of Asp351 allows a large conformational changes in cytoplasmic domains: the nucleotide binding domain and the phosphorylation domain are brought into close proximity. This rearrangement causes a 90° rotation of the activator domain, which leads to a rearrangement of the transmembrane helices. This rearrangement alters the affinity of the protein for the calcium and disrupts the calcium binding cavity. Calcium is released in the lumen of the endoplasmic reticulum/Golgi Apparatus or outside the cell. After releasing calcium, two protons are bound to the transport sites (charges compensation) and the aspartyl phosphate is hydrolyzed to complete the cycle.'''

'''The first step of the calcium pump catalytic cycle is the cooperative binding of <scene name='60/604489/Calcium_molecules/1'>two calcium ions</scene> in the calcium binding cavity. Then, ATP binds to the ATP binding site (nucleotide binding domain) and transfers its γ-phosphate to the aspartic acide 351 (phosphorylation domain). That creates a acid-stable aspartyl phosphate intermediate. The phosphorylation of Asp351 allows a large conformational changes in cytoplasmic domains: the nucleotide binding domain and the phosphorylation domain are brought into close proximity. This rearrangement causes a 90° rotation of the activator domain, which leads to a rearrangement of the transmembrane helices. This rearrangement alters the affinity of the protein for the calcium and disrupts the calcium binding cavity. Calcium is released in the lumen of the endoplasmic reticulum/Golgi Apparatus or outside the cell. After releasing calcium, two protons are bound to the transport sites (charges compensation) and the aspartyl phosphate is hydrolyzed to complete the cycle.'''

In the cytoplasm, the ATP binds to the cytosolic loop that connects transmembrane domains four and five (ATP binding site). It transfers its γ-phosphate to the aspartic acide 351 (phosphorylation site) and creates a acid-stable aspartyl phosphate intermediate. The binding of ATP is initiated by the cooperative fixing of two calcium ions to the transport site. The phosphorylation of Asp351 allows a large conformational changes in cytoplasmic domains which closes the ion gates from the cytoplasm and alters the affinity of the protein for the calcium. After releasing calcium (in the lumen of cytoplasm or out side the cell), two protons are bound to the transport sites (charges compensation) and the aspartyl phosphate is hydrolyzed to complete the cycle.

Sandbox Reserved 970: Difference between revisions

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@@ Line 3: / Line 3: @@
 == Introduction ==
-All living organisms depend on P-type ATPase to pump cation across the membrane. They play a fundamental role in their metabolism and physiology. Ca2+ ATPase, a P-type ATPase, transports calcium ions across the membrane against a concentration gradient. These pumps clear cytoplasm of the second messenger, the calcium. It's very important to keep a low concentration of calcium in the cell for a good cell signaling.
+All living organisms depend on P-type ATPase to pump cation across the membrane. They play a fundamental role in their metabolism and physiology. Ca2+ ATPase, a P-type ATPase, transports calcium ions across the membrane against a concentration gradient. These pumps clear cytoplasm of the second messenger, the calcium. It's very important to keep a low concentration of calcium in the cell for a good cell signaling.The hydrolysis of one adenosine triphosphate (ATP) is essential for the functioning of the pump and the transport of one calcium ion.
-We can found the PMCA (Plasma Membrane Ca2+ ATPase) which remove the calcium from the cell and the SERCA (Sarcoplasmic Endoplasmic Reticulum Ca2+ ATPase) which pumps calcium into the endoplasmic reticulum.
-The hydrolysis of one adenosine triphosphate (ATP) is essential for the functioning of the pump and the transport of one calcium ion.
@@ Line 22: / Line 20: @@
 The architecture of calcium ATPase (determined by X-Ray crystallography) allow to understand mechanisms by which the energy of ATP is coupled to the calcium transport across a membrane.
-'''The first step of the calcium pump catalytic cycle is the cooperative binding of two calcium ions in the calcium binding cavity. Then, ATP binds to the ATP binding site (nucleotide binding domain) and transfers its γ-phosphate to the aspartic acide 351 (phosphorylation domain). That creates a acid-stable aspartyl phosphate intermediate. The phosphorylation of Asp351 allows a large conformational changes in cytoplasmic domains: the nucleotide binding domain and the phosphorylation domain are brought into close proximity. This rearrangement causes a 90° rotation of the activator domain, which leads to a rearrangement of the transmembrane helices. This rearrangement alters the affinity of the protein for the calcium and disrupts the calcium binding cavity. Calcium is released in the lumen of the endoplasmic reticulum/Golgi Apparatus or outside the cell. After releasing calcium, two protons are bound to the transport sites (charges compensation) and the aspartyl phosphate is hydrolyzed to complete the cycle.'''
+'''The first step of the calcium pump catalytic cycle is the cooperative binding of <scene name='60/604489/Calcium_molecules/1'>two calcium ions</scene> in the calcium binding cavity. Then, ATP binds to the ATP binding site (nucleotide binding domain) and transfers its γ-phosphate to the aspartic acide 351 (phosphorylation domain). That creates a acid-stable aspartyl phosphate intermediate. The phosphorylation of Asp351 allows a large conformational changes in cytoplasmic domains: the nucleotide binding domain and the phosphorylation domain are brought into close proximity. This rearrangement causes a 90° rotation of the activator domain, which leads to a rearrangement of the transmembrane helices. This rearrangement alters the affinity of the protein for the calcium and disrupts the calcium binding cavity. Calcium is released in the lumen of the endoplasmic reticulum/Golgi Apparatus or outside the cell. After releasing calcium, two protons are bound to the transport sites (charges compensation) and the aspartyl phosphate is hydrolyzed to complete the cycle.'''
 In the cytoplasm, the ATP binds to the cytosolic loop that connects transmembrane domains four and five (ATP binding site). It transfers its γ-phosphate to the aspartic acide 351 (phosphorylation site) and creates a acid-stable aspartyl phosphate intermediate. The binding of ATP is initiated by the cooperative fixing of two calcium ions to the transport site. The phosphorylation of Asp351 allows a large conformational changes in cytoplasmic domains which closes the ion gates from the cytoplasm and alters the affinity of the protein for the calcium. After releasing calcium (in the lumen of cytoplasm or out side the cell), two protons are bound to the transport sites (charges compensation) and the aspartyl phosphate is hydrolyzed to complete the cycle.