Ca2+ Translocation across Sarcoplasmic Reticulum ATPase Randomizes the Two Transported Ions

Canet, Denis; Forge, Vincent; Guillain, Florent; Mintz, Elisabeth

doi:10.1074/jbc.271.34.20566

Cited by 11 publications

(4 citation statements)

References 27 publications

(20 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The phosphorylation-induced domain movements that close off cytoplasmic access to the cavity will initiate occlusion. If such movements involved M4, M5, or M6, they might also be expected to disrupt the precise placement of the ligands required to form high affinity sites, so that, after occlusion, the two Ca 2ϩ ions would be less firmly bound and capable of exchanging their positions, consistent with kinetic observations (49). Further long range, phosphorylation-induced domain movements will open the exit gate, permitting release of weakly bound Ca 2ϩ to the lumen.…”

Section: Mechanism Of Camentioning

confidence: 53%

The Mechanism of Ca2+ Transport by Sarco(Endo)plasmic Reticulum Ca2+-ATPases

MacLennan

Rice

Green³

1997

Journal of Biological Chemistry

459

369

View full text Add to dashboard Cite

Function Ca2ϩ pumps, together with Ca 2ϩ release channels, form ubiquitous Ca 2ϩ regulatory systems in muscle and non-muscle cells. The sarco(endo)plasmic reticulum Ca 2ϩ -ATPases (SERCA) 1 and the plasma membrane Ca 2ϩ -ATPases have the highest affinity for Ca 2ϩ removal from the cytoplasm and, together, set resting cytoplasmic Ca 2ϩ concentrations. Three differentially expressed genes encode SERCA proteins (1). SERCA1a and -1b are expressed in fast-twitch skeletal muscle, but loss of SERCA1 function in Brody disease is sufficiently compensated to preserve life (2). SERCA2a is the cardiac/slow-twitch isoform, whereas SERCA2b, with a C-terminal extension, is expressed in smooth muscle and non-muscle tissues. It is almost certainly an essential gene. SERCA3 is expressed in a limited set of non-muscle tissues, including endothelial, epithelial, and lymphocytic cells and platelets, and its knockout is not lethal (3).SERCA enzymes are typical of the class of P-type ATPases, which form a phosphoprotein intermediate and undergo conformational changes during the course of ATP hydrolysis (4, 5). Some of the conformational states can be stabilized, either by adjustment of reaction conditions or through mutagenesis, and characterized as intermediates in the overall reaction cycle (Fig. 1A). The phosphorylated intermediate, E 1 P(Ca) 2 , can phosphorylate ADP, whereas E 2 P can only react with water. The formation of E 1 P requires that two high affinity Ca 2ϩ binding sites be occupied. The enzyme is then phosphorylated by ATP and, concomitantly, the two Ca 2ϩ ions are occluded and can no longer exchange with cytoplasmic Ca 2ϩ . The rate-limiting transition to E 2 P is accompanied by loss of Ca 2ϩ into the lumen, the affinity having fallen by 3 orders of magnitude. Hydrolysis of E 2 P and regeneration of the high affinity Ca 2ϩ binding sites (E 1 (Ca) 2 ) complete the reversible cycle. High lumenal Ca 2ϩ drives the formation of E 1 P from phosphate (P i ), and its effect on the level of E 1 P led Jencks (5, 6) to postulate a second set of Ca 2ϩ

show abstract

Section: Mechanism Of Camentioning

confidence: 53%

The Mechanism of Ca2+ Transport by Sarco(Endo)plasmic Reticulum Ca2+-ATPases

MacLennan

Rice

Green³

1997

Journal of Biological Chemistry

459

369

View full text Add to dashboard Cite

show abstract

“…The change in Ca> a$nity for the second Ca> once the "rst one is bound must be a manifestation of some conformational change, which is identi"ed here with the E PE transconformation, as previously proposed (Dupont et al, 1982(Dupont et al, , 1988. Similarly, the release of the two Ca> into the SR lumen (Scheme Ib) has also been shown to occur sequentially (Inesi, 1987;Myung & Jencks, 1994;Forge et al, 1995: Canet et al, 1996.…”

Section: Methodsmentioning

confidence: 93%

Kinetic Analysis of a Model of the Sarcoplasmic Reticulum Ca-ATPase, with Variable Stoichiometry, which Enhances the Amount and the Rate of Ca Transport

Alonso

González

Takara

et al. 2001

Journal of Theoretical Biology

View full text Add to dashboard Cite

“…Whether this Ca 2+ release is sequential [45,[64][65][66] or not [62,63] has been debated. Even when sequential dissociation is observed, the two Ca 2+ seem to become mixed between binding and dissociation [67].…”

Section: Ca 2+ -Transportmentioning

confidence: 96%

Structural dynamics of the Ca²⁺-ATPase studied by time-resolved infrared spectroscopy

Barth

2008

Spectroscopy

View full text Add to dashboard Cite

This review discusses the contribution of time-resolved infrared spectroscopy to the understanding of the Ca2+pump in the sarcoplasmic reticulum membrane of skeletal muscle cells (SERCA1a). The focus is on interactions of the substrate ATP with the ATPase and on the bond parameters of the phosphoenzyme phosphate group. Functional groups throughout the ATP molecule are important for stabilising the closed conformation of the ATP–ATPase complex and for fast phosphorylation of the ATPase. Dissociation of the reaction product ADP after phosphorylation leads to a more open average conformation of the enzyme and does not trigger the transition from the first phosphoenzyme Ca2E1P to the second E2P. The P–O bond between phosphate and aspartyl moieties is weaker in Ca2E1P and E2P than in acetyl phosphate in aqueous solution, which explains the high reactivity of the phosphoenzymes. This ground state property of the phosphoenzymes prepares for a phosphate transfer reaction with dissociative character.

show abstract

Ca2+ Translocation across Sarcoplasmic Reticulum ATPase Randomizes the Two Transported Ions

Abstract: Cytoplasmic

Cited by 11 publications

References 27 publications

The Mechanism of Ca2+ Transport by Sarco(Endo)plasmic Reticulum Ca2+-ATPases

The Mechanism of Ca2+ Transport by Sarco(Endo)plasmic Reticulum Ca2+-ATPases

Kinetic Analysis of a Model of the Sarcoplasmic Reticulum Ca-ATPase, with Variable Stoichiometry, which Enhances the Amount and the Rate of Ca Transport

Structural dynamics of the Ca²⁺-ATPase studied by time-resolved infrared spectroscopy

Contact Info

Product

Resources

About

Ca2+ Translocation across Sarcoplasmic Reticulum ATPase Randomizes the Two Transported Ions

Abstract: Cytoplasmic

Cited by 11 publications

References 27 publications

The Mechanism of Ca2+ Transport by Sarco(Endo)plasmic Reticulum Ca2+-ATPases

The Mechanism of Ca2+ Transport by Sarco(Endo)plasmic Reticulum Ca2+-ATPases

Kinetic Analysis of a Model of the Sarcoplasmic Reticulum Ca-ATPase, with Variable Stoichiometry, which Enhances the Amount and the Rate of Ca Transport

Structural dynamics of the Ca2+-ATPase studied by time-resolved infrared spectroscopy

Contact Info

Product

Resources

About

Structural dynamics of the Ca²⁺-ATPase studied by time-resolved infrared spectroscopy