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 language | English (US) |
|---|---|
| Pages (from-to) | 190-196 |
| Number of pages | 7 |
| Journal | Biophysical journal |
| Volume | 67 |
| Issue number | 1 |
| DOIs | |
| State | Published - 1994 |
Bibliographical note
Funding Information:We thank Nicoleta Cornea, Robert L. H. Bennett, and Franz L. Nisswandt for technical assistance. This work was supported by a grant to D.D.T. from the American Heart Association, Minnesota Affiliate.