Molecular dynamics in mouse atrial tumor sarcoplasmic reticulum

John C Voss, J. E. Mahaney, L. R. Jones, D. D. Thomas

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

We have determined directly the effects of the inhibitory peptide phospholamban (PLB) on the rotational dynamics of the calcium pump (Ca- ATPase) of cardiac sarcoplasmic reticulum (SR). This was accomplished by comparing mouse ventricular SR, which has PLB levels similar to those found in other mammals, with mouse atrial SR, which is effectively devoid of PLB and thus has much higher (unregulated) calcium pump activity. To obtain sufficient quantities of atrial SR, we isolated the membranes from atrial tumor cells. We used time-resolved phosphorescence anisotropy of an erythrosin isothiocyanate label attached selectively and rigidly to the Ca- ATPase, to detect the microsecond rotational motion of the Ca-ATPase in the two preparations. The time-resolved phosphorescence anisotropy decays of both preparations at 25°C were multi-exponential, because of the presence of different oligomeric species. The rotational correlation times for the different oligomers were similar for the two preparations, but the total decay amplitude was substantially greater for atrial tumor SR, indicating that a smaller fraction of the Ca-ATPase molecules exists as large aggregates. Phosphorylation of PLB in ventricular SR decreased the population of large-scale Ca-ATPase aggregates to a level similar to that of atrial tumor SR. Lipid chain mobility (fluidity), detected by electron paramagnetic resonance of stearic acid spin labels, was very similar in the two preparations, indicating that the higher protein mobility in atrial tumor SR is not due to higher lipid fluidity. We conclude that PLB inhibits by inducing Ca-ATPase lateral aggregation, which can be relieved either by phosphorylating or removing PLB.

Original languageEnglish (US)
Pages (from-to)1787-1795
Number of pages9
JournalBiophysical Journal
Volume68
Issue number5
StatePublished - 1995
Externally publishedYes

Fingerprint

Sarcoplasmic Reticulum
Molecular Dynamics Simulation
Adenosine Triphosphatases
Neoplasms
Anisotropy
Erythrosine
Calcium
Lipids
Spin Labels
Electron Spin Resonance Spectroscopy
phospholamban
Mammals
Phosphorylation
Peptides
Membranes
Population

ASJC Scopus subject areas

  • Biophysics

Cite this

Voss, J. C., Mahaney, J. E., Jones, L. R., & Thomas, D. D. (1995). Molecular dynamics in mouse atrial tumor sarcoplasmic reticulum. Biophysical Journal, 68(5), 1787-1795.

Molecular dynamics in mouse atrial tumor sarcoplasmic reticulum. / Voss, John C; Mahaney, J. E.; Jones, L. R.; Thomas, D. D.

In: Biophysical Journal, Vol. 68, No. 5, 1995, p. 1787-1795.

Research output: Contribution to journalArticle

Voss, JC, Mahaney, JE, Jones, LR & Thomas, DD 1995, 'Molecular dynamics in mouse atrial tumor sarcoplasmic reticulum', Biophysical Journal, vol. 68, no. 5, pp. 1787-1795.
Voss JC, Mahaney JE, Jones LR, Thomas DD. Molecular dynamics in mouse atrial tumor sarcoplasmic reticulum. Biophysical Journal. 1995;68(5):1787-1795.
Voss, John C ; Mahaney, J. E. ; Jones, L. R. ; Thomas, D. D. / Molecular dynamics in mouse atrial tumor sarcoplasmic reticulum. In: Biophysical Journal. 1995 ; Vol. 68, No. 5. pp. 1787-1795.
@article{2844ccc908e0408fbe56d41feec04f78,
title = "Molecular dynamics in mouse atrial tumor sarcoplasmic reticulum",
abstract = "We have determined directly the effects of the inhibitory peptide phospholamban (PLB) on the rotational dynamics of the calcium pump (Ca- ATPase) of cardiac sarcoplasmic reticulum (SR). This was accomplished by comparing mouse ventricular SR, which has PLB levels similar to those found in other mammals, with mouse atrial SR, which is effectively devoid of PLB and thus has much higher (unregulated) calcium pump activity. To obtain sufficient quantities of atrial SR, we isolated the membranes from atrial tumor cells. We used time-resolved phosphorescence anisotropy of an erythrosin isothiocyanate label attached selectively and rigidly to the Ca- ATPase, to detect the microsecond rotational motion of the Ca-ATPase in the two preparations. The time-resolved phosphorescence anisotropy decays of both preparations at 25°C were multi-exponential, because of the presence of different oligomeric species. The rotational correlation times for the different oligomers were similar for the two preparations, but the total decay amplitude was substantially greater for atrial tumor SR, indicating that a smaller fraction of the Ca-ATPase molecules exists as large aggregates. Phosphorylation of PLB in ventricular SR decreased the population of large-scale Ca-ATPase aggregates to a level similar to that of atrial tumor SR. Lipid chain mobility (fluidity), detected by electron paramagnetic resonance of stearic acid spin labels, was very similar in the two preparations, indicating that the higher protein mobility in atrial tumor SR is not due to higher lipid fluidity. We conclude that PLB inhibits by inducing Ca-ATPase lateral aggregation, which can be relieved either by phosphorylating or removing PLB.",
author = "Voss, {John C} and Mahaney, {J. E.} and Jones, {L. R.} and Thomas, {D. D.}",
year = "1995",
language = "English (US)",
volume = "68",
pages = "1787--1795",
journal = "Biophysical Journal",
issn = "0006-3495",
publisher = "Biophysical Society",
number = "5",

}

TY - JOUR

T1 - Molecular dynamics in mouse atrial tumor sarcoplasmic reticulum

AU - Voss, John C

AU - Mahaney, J. E.

AU - Jones, L. R.

AU - Thomas, D. D.

PY - 1995

Y1 - 1995

N2 - We have determined directly the effects of the inhibitory peptide phospholamban (PLB) on the rotational dynamics of the calcium pump (Ca- ATPase) of cardiac sarcoplasmic reticulum (SR). This was accomplished by comparing mouse ventricular SR, which has PLB levels similar to those found in other mammals, with mouse atrial SR, which is effectively devoid of PLB and thus has much higher (unregulated) calcium pump activity. To obtain sufficient quantities of atrial SR, we isolated the membranes from atrial tumor cells. We used time-resolved phosphorescence anisotropy of an erythrosin isothiocyanate label attached selectively and rigidly to the Ca- ATPase, to detect the microsecond rotational motion of the Ca-ATPase in the two preparations. The time-resolved phosphorescence anisotropy decays of both preparations at 25°C were multi-exponential, because of the presence of different oligomeric species. The rotational correlation times for the different oligomers were similar for the two preparations, but the total decay amplitude was substantially greater for atrial tumor SR, indicating that a smaller fraction of the Ca-ATPase molecules exists as large aggregates. Phosphorylation of PLB in ventricular SR decreased the population of large-scale Ca-ATPase aggregates to a level similar to that of atrial tumor SR. Lipid chain mobility (fluidity), detected by electron paramagnetic resonance of stearic acid spin labels, was very similar in the two preparations, indicating that the higher protein mobility in atrial tumor SR is not due to higher lipid fluidity. We conclude that PLB inhibits by inducing Ca-ATPase lateral aggregation, which can be relieved either by phosphorylating or removing PLB.

AB - We have determined directly the effects of the inhibitory peptide phospholamban (PLB) on the rotational dynamics of the calcium pump (Ca- ATPase) of cardiac sarcoplasmic reticulum (SR). This was accomplished by comparing mouse ventricular SR, which has PLB levels similar to those found in other mammals, with mouse atrial SR, which is effectively devoid of PLB and thus has much higher (unregulated) calcium pump activity. To obtain sufficient quantities of atrial SR, we isolated the membranes from atrial tumor cells. We used time-resolved phosphorescence anisotropy of an erythrosin isothiocyanate label attached selectively and rigidly to the Ca- ATPase, to detect the microsecond rotational motion of the Ca-ATPase in the two preparations. The time-resolved phosphorescence anisotropy decays of both preparations at 25°C were multi-exponential, because of the presence of different oligomeric species. The rotational correlation times for the different oligomers were similar for the two preparations, but the total decay amplitude was substantially greater for atrial tumor SR, indicating that a smaller fraction of the Ca-ATPase molecules exists as large aggregates. Phosphorylation of PLB in ventricular SR decreased the population of large-scale Ca-ATPase aggregates to a level similar to that of atrial tumor SR. Lipid chain mobility (fluidity), detected by electron paramagnetic resonance of stearic acid spin labels, was very similar in the two preparations, indicating that the higher protein mobility in atrial tumor SR is not due to higher lipid fluidity. We conclude that PLB inhibits by inducing Ca-ATPase lateral aggregation, which can be relieved either by phosphorylating or removing PLB.

UR - http://www.scopus.com/inward/record.url?scp=0028962271&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0028962271&partnerID=8YFLogxK

M3 - Article

C2 - 7612820

AN - SCOPUS:0028962271

VL - 68

SP - 1787

EP - 1795

JO - Biophysical Journal

JF - Biophysical Journal

SN - 0006-3495

IS - 5

ER -