title: Neuronal activation by GPI-linked neuroligin-1 displayed in synthetic lipid bilayer membranes.
abstract: We have characterized, in vitro, interactions between hippocampal neuronal cells and silica microbeads coated with synthetic, fluid, lipid bilayer membranes containing the glycosylphosphatidyl inositol (GPI)-linked extracellular domain of the postsynaptic membrane protein neuroligin-1. These bilayer-neuroligin-1 beads activated neuronal cells to form presynaptic nerve terminals at the point of contact in a manner similar to that observed for live PC12 cells, ectopically expressing the full length neuroligin-1. The synthetic membranes exhibited biological activity at neuroligin-1 densities of approximately 1 to 6 proteins/microm(2). Polyolycarbonate beads with neuroligin-1 covalently attached to the surface failed to activate neurons despite the fact that neuroligin-1 binding activity is preserved. This implies that a lipid membrane environment is likely to be essential for neuroligin-1 activity. This technique allows the study of isolated proteins in an environment that has physical properties resembling those of a cell surface; proteins can diffuse freely within the membrane, retain their in vivo orientations, and are in a nondenatured state. In addition, the synthetic membrane environment affords control over both lipid and protein composition. This technology is easily implemented and can be applied to a wide variety of cellular studies.
authors.affiliation: Department of Chemistry, University of California Berkeley, 94720, USA.
authors.forename: Michael M
authors.initials: MM
authors.lastname: Baksh
authors.forename: Camin
authors.initials: C
authors.lastname: Dean
authors.forename: Sophie
authors.initials: S
authors.lastname: Pautot
authors.forename: Shannon
authors.initials: S
authors.lastname: DeMaria
authors.forename: Ehud
authors.initials: E
authors.lastname: Isacoff
authors.forename: Jay T
authors.initials: JT
authors.lastname: Groves
mesh_terms: D000818:Animals; D015816:Cell Adhesion Molecules, Neuronal; D002460:Cell Line; D017261:Glycosylphosphatidylinositols / Q000378:metabolism*; D006801:Humans; D008051:Lipid Bilayers; D008565:Membrane Proteins / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D051381:Rats
chemical_list: D015816:Cell Adhesion Molecules, Neuronal; D017261:Glycosylphosphatidylinositols; D008051:Lipid Bilayers; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; C093438:neuroligin 1