Phospholamban forms Ca2+-selective channels in lipid bilayers

R. J. Kovacs, M. T. Nelson, H. K.B. Simmerman, L. R. Jones

Research output: Contribution to journalArticle

109 Scopus citations

Abstract

Phospholamban is the major membrane protein of the heart phosphorylated in response to β-adrenergic stimulation. A role for phospholamban in the control of Ca2+ transport by the sarcoplasmic reticulum has been postulated, but the mechanism is incompletely understood. Structural characterization of the purified protein suggests that it is capable of forming a membrane-spanning pore (Simmerman, H.K.B., Collins, J.H., Theibert, J.L., Wegener, A.D., and Jones, L.R. (1986) J. Biol. Chem. 261, 13333-13341). The experiments described here tested the hypothesis that canine cardiac phospholamban, isolated in the fully dephosphorylated state, forms ion channels in lipid bilayers. Phospholamban purified by two different methods formed channels that were permeable to cations, exhibited spontaneous openings and closings, and were selective for Ca2+ over K+. Dihydropyridine drugs and ryanodine did not affect channel activity. The putative membrane-spanning portion of the molecule, residues 26-52, also formed channels in the bilayer. The putative regulatory portion of the molecule, residues 2-25, did not. The results suggest that phospholamban may regulate sarcoplasmic reticulum Ca2+ flux by acting as a Ca2+ channel.

Original languageEnglish (US)
Pages (from-to)18364-18368
Number of pages5
JournalJournal of Biological Chemistry
Volume263
Issue number34
StatePublished - Jan 1 1988
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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