Three experimental systems are described including sarcoplasmic reticulum (SR) vesicles, reconstituted proteoliposomes, and recombinant protein obtained by gene transfer and expression in foreign cells. It is shown that the Ca2+ ATPase of sarcoplasmic reticulum (SR) includes an extramembranous globular head which is connected through a stalk to a membrane bound region. Cooperative binding of two calcium ions occurs sequentially, within a channel formed by four clustered helices within the membrane bound region. Destabilization of the helical cluster is produced following enzyme phosphorylation by ATP at the catalytic site in the extramembranous region. The affinity and orientation of the Ca2+ binding site are thereby changed, permitting vectorial dissociation of bound Ca2+ against a concentration gradient. A long range linkage between phosphorylation and Ca2+ binding sites is provided by an intervening peptide segment that retains high homology in cation transport ATPases, and whose function is highly sensitive to mutational perturbations.
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Review Article|
October 01 1995
Ca2+ binding and translocation by the sarcoplasmic reticulum ATPase: Functional and structural considerations
Giuseppe Inesi;
Giuseppe Inesi
1Department of Biological Chemistry, University of Maryland School of Medicine, Baltimore, Maryland 21201
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Li Chen;
Li Chen
1Department of Biological Chemistry, University of Maryland School of Medicine, Baltimore, Maryland 21201
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Carlota Sumbilla;
Carlota Sumbilla
1Department of Biological Chemistry, University of Maryland School of Medicine, Baltimore, Maryland 21201
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David Lewis;
David Lewis
1Department of Biological Chemistry, University of Maryland School of Medicine, Baltimore, Maryland 21201
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Mary E. Kirtley
Mary E. Kirtley
1Department of Biological Chemistry, University of Maryland School of Medicine, Baltimore, Maryland 21201
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Publisher: Portland Press Ltd
Received:
September 14 1995
Online ISSN: 1573-4935
Print ISSN: 0144-8463
© 1995 Plenum Publishing Corporation
1995
Biosci Rep (1995) 15 (5): 327–339.
Article history
Received:
September 14 1995
Citation
Giuseppe Inesi, Li Chen, Carlota Sumbilla, David Lewis, Mary E. Kirtley; Ca2+ binding and translocation by the sarcoplasmic reticulum ATPase: Functional and structural considerations. Biosci Rep 1 October 1995; 15 (5): 327–339. doi: https://doi.org/10.1007/BF01788365
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