Phosphoryl Transfer and Calcium Ion Occlusion in the Calcium Pump
Copyright policy )Phosphoryl Transfer and Calcium Ion Occlusion in the Calcium Pump
A tight coupling between adenosine triphosphate (ATP) hydrolysis and vectorial ion transport has to be maintained by ATP-consuming ion pumps. We report two crystal structures of Ca 2+ -bound sarco(endo)plasmic reticulum Ca 2+ –adenosine triphosphatase (SERCA) at 2.6 and 2.9 angstrom resolution in complex with (i) a nonhydrolyzable ATP analog [adenosine (β–γ methylene)–triphosphate] and (ii) adenosine diphosphate plus aluminum fluoride. SERCA reacts with ATP by an associative mechanism mediated by two Mg 2+ ions to form an aspartyl-phosphorylated intermediate state (Ca 2 -E1∼P). The conformational changes that accompany the reaction with ATP pull the transmembrane helices 1 and 2 and close a cytosolic entrance for Ca 2+ , thereby preventing backflow before Ca 2+ is released on the other side of the membrane.
- Aarhus University Denmark
Models, Molecular, Binding Sites, Protein Conformation, Calcium-Transporting ATPases, Crystallography, X-Ray, Protein Structure, Secondary, Protein Structure, Tertiary, Sarcoplasmic Reticulum Calcium-Transporting ATPases, Adenosine Diphosphate, Fluorides, Adenosine Triphosphate, Cytosol, Muscle Fibers, Fast-Twitch, Animals, Calcium, Rabbits, Phosphorylation, Aluminum Compounds, Crystallization
Models, Molecular, Binding Sites, Protein Conformation, Calcium-Transporting ATPases, Crystallography, X-Ray, Protein Structure, Secondary, Protein Structure, Tertiary, Sarcoplasmic Reticulum Calcium-Transporting ATPases, Adenosine Diphosphate, Fluorides, Adenosine Triphosphate, Cytosol, Muscle Fibers, Fast-Twitch, Animals, Calcium, Rabbits, Phosphorylation, Aluminum Compounds, Crystallization
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