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Lipid-protein interactions with cardiac phospholamban studied by spin-label electron spin resonance

Lipid-protein interactions with cardiac phospholamban studied by spin-label electron spin resonance
Lipid-protein interactions with cardiac phospholamban studied by spin-label electron spin resonance
Phospholamban is a cardiac regulatory protein that, in its monomeric form, inhibits the Ca2+-ATPase. Lipid-protein interactions with a synthetic variant of phospholamban, in which all cysteine residues are replaced with alanine, have been studied by spin-label electron spin resonance (ESR) in different lipid host membranes. Both the stoichiometry and selectivity of lipid interactions were determined from the two-component ESR spectra of phospholipid species spin-labeled on the 14 C atom of the sn-2 chain. The lipid stoichiometry is determined by the oligomeric state of the protein and the selectivity by the membrane disposition of the positively charged residues in the N-terminal section of the protein. In dimyristoylphosphatidylcholine (DMPC) membranes, the stoichiometry (Nb) is 7 lipids/monomer for the full-length protein and 4 for the transmembrane section (residues 26-52). These stoichiometries correspond to the dimeric and pentameric forms, respectively. In palmitoyloleoylphosphatidylcholine, Nb = 4 for both the whole protein and the transmembrane peptide. In negatively charged membranes of dimyristoylphosphatidylglycerol (DMPG), the lipid stoichiometry is Nb = 10-11 per monomer for both the full-length protein and the transmembrane peptide. This stoichiometry corresponds to monomeric dispersion of the protein in the negatively charged lipid. The sequence of lipid selectivity is as follows: stearic acid > phosphatidic acid > phosphatidylserine = phosphatidylglycerol = phosphatidylcholine > phosphatidylethanolamine for both the full-length protein and the transmembrane peptide in DMPC. Absolute selectivities are, however, lower for the transmembrane peptide. A similar pattern of lipid selectivity is obtained in DMPG, but the absolute selectivities are reduced considerably. The results are discussed in terms of the integration of the regulatory species in the lipid membrane.
0006-2960
5151-5158
Arora, Ashish
d6dc4e77-58fd-4e0b-b907-3ed5abb10bbe
Williamson, Ian M.
73f00143-e678-4e05-8f99-1aa39f569aaf
Lee, Anthony G.
0891914c-e0e2-4ee1-b43e-1b70eb072d8e
Marsh, Derek
e2ab9365-4e03-43f2-8abe-cb03f222e7ae
Arora, Ashish
d6dc4e77-58fd-4e0b-b907-3ed5abb10bbe
Williamson, Ian M.
73f00143-e678-4e05-8f99-1aa39f569aaf
Lee, Anthony G.
0891914c-e0e2-4ee1-b43e-1b70eb072d8e
Marsh, Derek
e2ab9365-4e03-43f2-8abe-cb03f222e7ae

Arora, Ashish, Williamson, Ian M., Lee, Anthony G. and Marsh, Derek (2003) Lipid-protein interactions with cardiac phospholamban studied by spin-label electron spin resonance. Biochemistry, 42 (17), 5151-5158. (doi:10.1021/bi020663o).

Record type: Article

Abstract

Phospholamban is a cardiac regulatory protein that, in its monomeric form, inhibits the Ca2+-ATPase. Lipid-protein interactions with a synthetic variant of phospholamban, in which all cysteine residues are replaced with alanine, have been studied by spin-label electron spin resonance (ESR) in different lipid host membranes. Both the stoichiometry and selectivity of lipid interactions were determined from the two-component ESR spectra of phospholipid species spin-labeled on the 14 C atom of the sn-2 chain. The lipid stoichiometry is determined by the oligomeric state of the protein and the selectivity by the membrane disposition of the positively charged residues in the N-terminal section of the protein. In dimyristoylphosphatidylcholine (DMPC) membranes, the stoichiometry (Nb) is 7 lipids/monomer for the full-length protein and 4 for the transmembrane section (residues 26-52). These stoichiometries correspond to the dimeric and pentameric forms, respectively. In palmitoyloleoylphosphatidylcholine, Nb = 4 for both the whole protein and the transmembrane peptide. In negatively charged membranes of dimyristoylphosphatidylglycerol (DMPG), the lipid stoichiometry is Nb = 10-11 per monomer for both the full-length protein and the transmembrane peptide. This stoichiometry corresponds to monomeric dispersion of the protein in the negatively charged lipid. The sequence of lipid selectivity is as follows: stearic acid > phosphatidic acid > phosphatidylserine = phosphatidylglycerol = phosphatidylcholine > phosphatidylethanolamine for both the full-length protein and the transmembrane peptide in DMPC. Absolute selectivities are, however, lower for the transmembrane peptide. A similar pattern of lipid selectivity is obtained in DMPG, but the absolute selectivities are reduced considerably. The results are discussed in terms of the integration of the regulatory species in the lipid membrane.

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Submitted date: 18 November 2002
Published date: 6 May 2003

Identifiers

Local EPrints ID: 56742
URI: https://eprints.soton.ac.uk/id/eprint/56742
ISSN: 0006-2960
PURE UUID: 2c0a0e64-158d-454a-875f-b36c6bdaab46

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Date deposited: 07 Aug 2008
Last modified: 13 Mar 2019 20:34

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Contributors

Author: Ashish Arora
Author: Ian M. Williamson
Author: Anthony G. Lee
Author: Derek Marsh

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