title: Analysis of the contribution of saturated and polyunsaturated phospholipid monolayers to the binding of proteins.
abstract: The binding of peripheral proteins to membranes results in different biological effects. The large diversity of membrane lipids is thought to modulate the activity of these proteins. However, information on the selective binding of peripheral proteins to membrane lipids is still largely lacking. Lipid monolayers at the air/water interface are useful model membrane systems for studying the parameters responsible for peripheral protein membrane binding. We have thus measured the maximum insertion pressure (MIP) of two proteins from the photoreceptors, Retinitis pigmentosa 2 (RP2) and recoverin, to estimate their binding to lipid monolayers. Photoreceptor membranes have the unique characteristic that more than 60% of their fatty acids are polyunsaturated, making them the most unsaturated natural membranes known to date. These membranes are also thought to contain significant amounts of saturated phospholipids. MIPs of RP2 and recoverin have thus been measured in the presence of saturated and polyunsaturated phospholipids. MIPs higher than the estimated lateral pressure of biomembranes have been obtained only with a saturated phospholipid for RP2 and with a polyunsaturated phospholipid for recoverin. A new approach was then devised to analyze these data properly. In particular, a parameter called the synergy factor allowed us to highlight the specificity of RP2 for saturated phospholipids and recoverin for polyunsaturated phospholipids as well as to demonstrate clearly the preference of RP2 for saturated phospholipids that are known to be located in microdomains.
authors.affiliation: LOEX/CUO-Recherche, Centre Hospitalier Affilié Universitaire de Québec, Département d'Ophtalmologie, Faculté de Médecine, Université Laval, Québec, Québec, Canada.
authors.forename: Philippe
authors.initials: P
authors.lastname: Calvez
authors.forename: Eric
authors.initials: E
authors.lastname: Demers
authors.forename: Elodie
authors.initials: E
authors.lastname: Boisselier
authors.forename: Christian
authors.initials: C
authors.lastname: Salesse
mesh_terms: D005136:Eye Proteins / Q000737:chemistry / Q000378:metabolism; D005227:Fatty Acids / Q000737:chemistry*; D005231:Fatty Acids, Unsaturated / Q000737:chemistry*; D019204:GTP-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism; D008567:Membranes, Artificial; D010743:Phospholipids / Q000737:chemistry*; D011485:Protein Binding; D051603:Recoverin / Q000737:chemistry / Q000378:metabolism
chemical_list: D005136:Eye Proteins; D005227:Fatty Acids; D005231:Fatty Acids, Unsaturated; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D008567:Membranes, Artificial; D010743:Phospholipids; C072178:RP2 protein, human; D051603:Recoverin; D019204:GTP-Binding Proteins