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March 1, 1980Journal of Biological ChemistryOpen Access

cAMP-dependent phosphorylation of phospholamban markedly increased the initial rates of EP formation and calcium binding in Ca2+-free microsomes.

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Population

Cardiac microsomes (sarcoplasmic reticulum)

Comparison

Incubation with cAMP-dependent protein kinase vs Incubation without cAMP-dependent protein kinase

Design

Preclinical

Authors

MTMichihiko TadaMYMakoto YamadaFOFumio Ohmori

Discussion

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Overview

Accelerates mechanistic insight into SR calcium handling; leaves open translation to human cardiac physiology or therapy.

Key Points

  • This study investigates the influence of phospholamban phosphorylation on Ca2+-dependent ATPase activity in cardiac sarcoplasmic reticulum.
  • Transient kinetic analysis of ATPase dynamics via rapid quenching device after incubation with and without cyclic AMP-dependent protein kinase.
  • Evaluation of calcium binding and EP formation in Ca2+-free and Ca2+-bound microsomes with varying ATP concentrations.
  • Comparison of initial rates and maximal EP formation using phosphorylated versus non-phosphorylated preparations.
  • In Ca2+-free microsomes, phosphorylated ATPase showed enhanced initial rates of EP formation and calcium binding compared to non-phosphorylated.
  • Significant enhancement of EP formation occurred with greater than 10 µM ATP, while lower ATP concentrations reduced this effect.
  • Phospholamban phosphorylation notably increases the rate of calcium translocation across the microsomal membrane.

Structured PICO

P
Population
Cardiac microsomes (sarcoplasmic reticulum)
I
Intervention
Incubation with cAMP-dependent protein kinase (phosphorylation of phospholamban)
C
Comparator
Incubation without cAMP-dependent protein kinase
O
Outcome
Transient kinetics of the formation of the phosphorylated intermediate EP of ATPase and calcium bindingsurrogate

Phosphorylation of phospholamban by cAMP-dependent protein kinase accelerates calcium binding and translocation across the cardiac sarcoplasmic reticulum membrane.

Cite This Study

Tada et al. (1980) studied this question.

synapsesocial.com/papers/6a24b5d78c55644ebb279b62https://doi.org/10.1016/s0021-9258(19)85980-x
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