%0 Journal Article
%T Palmitoylation and membrane cholesterol stabilize ¦Ì-opioid receptor homodimerization and G protein coupling
%A Hui Zheng
%A Elizabeth A Pearsall
%A Dow P Hurst
%A Yuhan Zhang
%A Ji Chu
%A Yali Zhou
%A Patricia H Reggio
%A Horace H Loh
%A Ping-Yee Law
%J BMC Cell Biology
%D 2012
%I BioMed Central
%R 10.1186/1471-2121-13-6
%X C3.55(170) was determined to be the palmitoylation site of OPRM1. Mutation of this Cys to Ala did not affect the binding of agonists, but attenuated receptor signaling and decreased cholesterol associated with the receptor signaling complex. In addition, both attenuation of receptor palmitoylation (by mutation of C3.55[170] to Ala) and inhibition of cholesterol synthesis (by treating the cells with simvastatin, a HMG-CoA reductase inhibitor) impaired receptor signaling, possibly by decreasing receptor homodimerization and G¦Ái2 coupling; this was demonstrated by co-immunoprecipitation, immunofluorescence colocalization and fluorescence resonance energy transfer (FRET) analyses. A computational model of the OPRM1 homodimer structure indicated that a specific cholesterol-palmitoyl interaction can facilitate OPRM1 homodimerization at the TMH4-TMH4 interface.We demonstrate that C3.55(170) is the palmitoylation site of OPRM1 and identify a cholesterol-palmitoyl interaction in the OPRM1 complex. Our findings suggest that this interaction contributes to OPRM1 signaling by facilitating receptor homodimerization and G protein coupling. This conclusion is supported by computational modeling of the OPRM1 homodimer.A cholesterol-palmitoyl interaction at C7.68(341) has been observed in the crystallographic dimeric interface of transmembrane helix (TMH) 1 and Helix 8 in the ¦Â2-adrenergic receptor (¦Â2-AR) crystal structure [1]. Palmitoylation is a covalent attachment of palmitic acid to cysteine residues of membrane proteins. Palmitoylation of the rhodopsin sub-family of G protein-coupled receptors (GPCRs) has been universally reported, and similar cholesterol-palmitoyl interactions may exist within other GPCRs. Sequence alignment has identified cysteine residues in the carboxy termini as potential palmitoylation sites in about 78% of 74 GPCRs examined [2]. However, these cysteines are not the only palmitoylation sites. For example, although rat ¦Ì-opioid receptor (OPRM1) has two cy
%K Palmitoylation
%K Cholesterol
%K Homodimerization
%K G protein coupling
%U http://www.biomedcentral.com/1471-2121/13/6