Partition profile of the nicotinic acetylcholine receptor in lipid domains upon reconstitution.
The nicotinic acetylcholine receptor (AChR) is in intimate contact with the lipids in its native membrane. Here we analyze the possibility that it is the intrinsic properties of the AChR that determine its partition into a given lipid domain. Torpedo AChR or a synthetic peptide corresponding to the AChR M4 segment (the one in closer contact with lipids) was reconstituted into "raft"-containing model membranes. The distribution of the AChR was assessed by Triton X-100 extraction in combination with fluorescence studies, and lipid analyses were performed on each sample. The influence of rapsyn, a peripheral protein involved in AChR aggregation, was studied. Raft-like domain aggregation was also studied using membranes containing the ganglioside GM1 followed by GM1 crosslinking. The gammaM4 peptide displays a marked preference for raft-like domains. In contrast, AChR alone or in the presence of rapsyn or ganglioside aggregation exhibits no such preference for raft-like domains, but it does cause a significant reduction in the total amount of these domains. The results indicate that the distribution of the AChR in lipid domains cannot be due exclusively to the intrinsic physicochemical properties of the protein and that there must be an external signal in native cell membranes that directs the AChR to a specific membrane domain.
Instituto de Investigaciones Bioquímicas de Bahía Blanca, Consejo Nacional de Investigaciones Científicas y Técnicas, and UNESCO Chair of Biophysics and Molecular Neurobiology, Universidad Nacional del Sur, Buenos Aires, Argentina.
Vicente
V
Bermúdez
Silvia S
SS
Antollini
Gaspar A
GA
Fernández Nievas
Marta I
MI
Aveldaño
Francisco J
FJ
Barrantes
D000818:Animals; D003902:Detergents / Q000737:chemistry; D031541:Fluorescence Resonance Energy Transfer; D008563:Membrane Lipids / Q000737:chemistry* / Q000378:metabolism; D021962:Membrane Microdomains / Q000737:chemistry* / Q000378:metabolism; D010455:Peptides / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011978:Receptors, Nicotinic / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D014101:Torpedo
D003902:Detergents; D008563:Membrane Lipids; D010455:Peptides; D011978:Receptors, Nicotinic