title: Functional evidence for presence of lipid rafts in erythrocyte membranes: Gsalpha in rafts is essential for signal transduction.
abstract: Membrane microdomains enriched in cholesterol and sphingolipids and containing specific membrane proteins are designated as lipid rafts. Lipid rafts have been implicated in cell signaling pathways in various cell types. Heterotrimeric guanine nucleotide-binding protein (Gsalpha) has been shown to be a raft component of erythrocytes and has been implicated in cell signaling. Rafts are isolated as detergent-resistant microdomains (DRMs) for biochemical analysis. Cholesterol depletion is widely used to disrupt raft structures to study their function in biological membranes. In the present study, we developed an alternate strategy for disrupting raft structures without altering membrane cholesterol content. Lidocaine hydrochloride, an amphipathic local anesthetic, is shown to reversibly disrupt rafts in erythrocyte membranes and alter the Gsalpha dependent signal transduction pathway. These findings provide evidence for the presence of rafts while maintaining normal cholesterol content in erythrocyte membranes and confirm a role for raft-associated Gsalpha in signal transduction in erythrocytes.
authors.affiliation: Department of Biochemistry, Tokyo Women's Medical University, Tokyo, Japan.
authors.forename: Kotoe
authors.initials: K
authors.lastname: Kamata
authors.forename: Sumie
authors.initials: S
authors.lastname: Manno
authors.forename: Makoto
authors.initials: M
authors.lastname: Ozaki
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Takakuwa
mesh_terms: D000241:Adenosine / Q000502:physiology; D000328:Adult; D000779:Anesthetics, Local / Q000494:pharmacology; D002148:Calmodulin-Binding Proteins / Q000097:blood* / Q000737:chemistry; D002784:Cholesterol / Q000378:metabolism; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000378:metabolism*; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000097:blood / Q000502:physiology*; D006801:Humans; D008012:Lidocaine / Q000494:pharmacology; D008563:Membrane Lipids / Q000378:metabolism; D021962:Membrane Microdomains / Q000187:drug effects / Q000502:physiology*; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D043705:Receptor, Adenosine A2A / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*; D047392:beta-Cyclodextrins / Q000494:pharmacology; D000099291:Adducins
chemical_list: D000241:Adenosine; D000779:Anesthetics, Local; D002148:Calmodulin-Binding Proteins; D002784:Cholesterol; D019205:GTP-Binding Protein alpha Subunits, Gs; D008012:Lidocaine; D008563:Membrane Lipids; D043705:Receptor, Adenosine A2A; D047392:beta-Cyclodextrins; D000099291:Adducins; C108732:methyl-beta-cyclodextrin