1. Centre for Membrane Pumps in Cells and Disease—PUMPKIN, Danish National Research Foundation, and,
2. Institute of Physiology and Biophysics, University of Aarhus, Ole Worms Alle, blg. 1185, DK - 8000 Aarhus C, Denmark
3. Department of Molecular Biology, University of Aarhus, Gustav Wieds Vej 10C, DK - 8000 Aarhus C, Denmark
4. Present address: Laboratoire de Cristallographie et RMN biologiques, UMR 8015 CNRS, Faculté de Pharmacie. Université Paris Descartes, 4 avenue de l'Observatoire, 75270 Paris Cedex 06, France.

Correspondence to: Jesper Vuust Møller^1,2Poul Nissen^1,3 Correspondence and requests for materials should be addressed to P.N. (Email: pn@mb.au.dk) and J.V.M. (Email: jvm@biophys.au.dk).

Abstract

The sarcoplasmic reticulum Ca²⁺-ATPase, a P-type ATPase, has a critical role in muscle function and metabolism. Here we present functional studies and three new crystal structures of the rabbit skeletal muscle Ca²⁺-ATPase, representing the phosphoenzyme intermediates associated with Ca²⁺ binding, Ca²⁺ translocation and dephosphorylation, that are based on complexes with a functional ATP analogue, beryllium fluoride and aluminium fluoride, respectively. The structures complete the cycle of nucleotide binding and cation transport of Ca²⁺-ATPase. Phosphorylation of the enzyme triggers the onset of a conformational change that leads to the opening of a luminal exit pathway defined by the transmembrane segments M1 through M6, which represent the canonical membrane domain of P-type pumps. Ca²⁺ release is promoted by translocation of the M4 helix, exposing Glu 309, Glu 771 and Asn 796 to the lumen. The mechanism explains how P-type ATPases are able to form the steep electrochemical gradients required for key functions in eukaryotic cells.

1. Centre for Membrane Pumps in Cells and Disease—PUMPKIN, Danish National Research Foundation, and,
2. Institute of Physiology and Biophysics, University of Aarhus, Ole Worms Alle, blg. 1185, DK - 8000 Aarhus C, Denmark
3. Department of Molecular Biology, University of Aarhus, Gustav Wieds Vej 10C, DK - 8000 Aarhus C, Denmark
4. Present address: Laboratoire de Cristallographie et RMN biologiques, UMR 8015 CNRS, Faculté de Pharmacie. Université Paris Descartes, 4 avenue de l'Observatoire, 75270 Paris Cedex 06, France.

Correspondence to: Jesper Vuust Møller^1,2Poul Nissen^1,3 Correspondence and requests for materials should be addressed to P.N. (Email: pn@mb.au.dk) and J.V.M. (Email: jvm@biophys.au.dk).

MORE ARTICLES LIKE THIS

These links to content published by NPG are automatically generated.