Sandbox Reserved 970: Difference between revisions
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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 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 <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. | 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 <scene name='60/604489/Asp_351/1'>aspartic acide 351</scene> (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. | ||
[[Image:51-TheCalciumPumps-calcium-pumps.jpg|400px|center|]]<ref name="second"> David Goodsell, 2004 - Calcium pump molecul of the month - PDB, doi: 10.2210/rcsb_pdb/mom_2004_3</ref> | [[Image:51-TheCalciumPumps-calcium-pumps.jpg|400px|center|]]<ref name="second"> David Goodsell, 2004 - Calcium pump molecul of the month - PDB, doi: 10.2210/rcsb_pdb/mom_2004_3</ref> | ||
