The prototypical Torpedo nicotinic acetylcholine receptor does not exhibit preferential partition into raft-like lipid domains upon reconstitution.

BERMÚDEZ, V.; ANTOLLINI, S. S.; FERNÁNDEZ NIEVAS, G. A.; AVELDAÑO, M. I.; BARRANTES, F. J.

JLR PAPERS IN PRESS

AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC

Año: 2010 vol. 51 p. 2629 - 2641

0022-2275

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 fl uorescence studies, and lipid analyses were performed on each sample. The infl uence 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  M4 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 signifi cant 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.