The physical mechanism of calcium pump regulation in the heart

J. Voss, L. R. Jones, D. D. Thomas

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Abstract

The Ca-ATPase in the cardiac sarcoplasmic reticulum membrane is regulated by an amphipathic transmembrane protein, phospholamban. We have used time-resolved phosphorescence anisotropy to detect the microsecond rotational dynamics, and thereby the self-association, of the Ca-ATPase as a function of phospholamban phosphorylation and physiologically relevant calcium levels. The phosphorylation of phospholamban increases the rotational mobility of the Ca-ATPase in the sarcoplasmic reticulum bilayer, due to a decrease in large-scale protein association, with a [Ca2+] dependence parallel to that of enzyme activation. These results support a model in which phospholamban phosphorylation or calcium free the enzyme from a kinetically unfavorable associated state.

Original languageEnglish (US)
Pages (from-to)190-196
Number of pages7
JournalBiophysical journal
Volume67
Issue number1
DOIs
StatePublished - Jan 1 1994

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ASJC Scopus subject areas

  • Biophysics

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