title: MPP1 as a Factor Regulating Phase Separation in Giant Plasma Membrane-Derived Vesicles.
abstract: The existence of membrane-rafts helps to conceptually understand the spatiotemporal organization of membrane-associated events (signaling, fusion, fission, etc.). However, as rafts themselves are nanoscopic, dynamic, and transient assemblies, they cannot be directly observed in a metabolizing cell by traditional microscopy. The observation of phase separation in giant plasma membrane-derived vesicles from live cells is a powerful tool for studying lateral heterogeneity in eukaryotic cell membranes, specifically in the context of membrane rafts. Microscopic phase separation is detectable by fluorescent labeling, followed by cooling of the membranes below their miscibility phase transition temperature. It remains unclear, however, if this lipid-driven process is tuneable in any way by interactions with proteins. Here, we demonstrate that MPP1, a member of the MAGUK family, can modulate membrane properties such as the fluidity and phase separation capability of giant plasma membrane-derived vesicles. Our data suggest that physicochemical domain properties of the membrane can be modulated, without major changes in lipid composition, through proteins such as MPP1.
authors.affiliation: Laboratory of Cytobiochemistry, Faculty of Biotechnology, University of Wrocław, Wrocław, Poland; Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.
authors.forename: Joanna
authors.initials: J
authors.lastname: Podkalicka
authors.affiliation: Laboratory of Cytobiochemistry, Faculty of Biotechnology, University of Wrocław, Wrocław, Poland.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Biernatowska
authors.affiliation: Laboratory of Cytobiochemistry, Faculty of Biotechnology, University of Wrocław, Wrocław, Poland.
authors.forename: Michał
authors.initials: M
authors.lastname: Majkowski
authors.affiliation: Paul Langerhans Institute Dresden of the Helmholtz Centre Munich at the University Clinic Carl Gustav Carus, TU Dresden, Dresden, Germany; German Center for Diabetes Research (DZD e.v.), Neuherberg, Germany.
authors.forename: Michał
authors.initials: M
authors.lastname: Grzybek
authors.affiliation: Laboratory of Cytobiochemistry, Faculty of Biotechnology, University of Wrocław, Wrocław, Poland. Electronic address: afsbc@ibmb.uni.wroc.pl.
authors.forename: Aleksander F
authors.initials: AF
authors.lastname: Sikorski
mesh_terms: D001798:Blood Proteins / Q000378:metabolism*; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism*; D055252:Cell-Derived Microparticles / Q000378:metabolism*; D006801:Humans; D008560:Membrane Fluidity; D008565:Membrane Proteins / Q000378:metabolism*
chemical_list: D001798:Blood Proteins; C089465:MPP1 protein, human; D008565:Membrane Proteins