Nonequilibrium Adhesion Patterns at Lipid Bilayer Junctions

Proc. Natl. Acad. Sci. U.S.A.

2004

Self Cite

We introduce a simple intermembrane junction system in which to explore pattern and structure formation by membrane-bound proteins. The junction consists of a planar lipid bilayer to which one species of protein (an IgG antibody) is bound, forming a 2D, compressible fluid. Upon the adhesion of a second lipid bilayer, the formerly uniformly distributed proteins rapidly reorganize into patterns of dense and sparse zones. Using a combination of complementary imaging techniques (fluorescence microscopy, fluorescence interference contrast microscopy, and fluorescence resonance energy transfer), we reconstruct the 3D structure of these intermembrane patterns with nanometer-scale topographic resolution, revealing the orientation of the proteins. The patterns form as the rapid bilayer-bilayer adhesion, often radiating outward from an initial, circular contact site, pushes aside the antibodies, sweeping them into areas of high density and clearing low-density regions. Coarsening of these local features is energetically costly and therefore kinetically trapped; the patterns do not change over tens of minutes. These studies demonstrate that membrane mechanical forces alone, i.e., in the absence of specific biochemical interactions, can drive m-scale organization of membrane proteins.

mentioning

confidence: 99%

Protein patterns at lipid bilayer junctions

Parthasarathy

Proc. Natl. Acad. Sci. U.S.A.

2004

Self Cite

“…A third type of intermembrane junction can be formed by rupture of GUVs onto supported membranes. This technique produces planar junctions, with typical sizes of 10–50 μm, which exhibit multiple adhesion states and are well suited to optical and scanning probe imaging techniques 112–115. This type of supported membrane junction has proven useful in the study of membrane‐mediated reorganization of proteins into patterned states,23 and is discussed further in Section 4.2 in the context of membrane topographical imaging.…”

Section: Experimental Model Systemsmentioning

confidence: 99%

“…The reflection coefficient of the silicon/silicon oxide interface (0.46 at 645 nm) is represented by r f . This approximation has a maximum error of about 2 nm over the distance range of typical experiments involving supported membrane junctions (5–75 nm); more involved calculations include the angular spread of incident and collected light as well as spectral bandwidth 115. 130–132…”

Section: Imaging Techniquesmentioning

confidence: 99%

“…FLIC imaging is instrumental in making these types of distinctions. Intermembrane FRET has been used to additionally confirm that valleys observed in the upper membrane of the protein intermembrane junction descend to within a few nanometers of the lower membrane 115. The combined use of intermembrane FRET can increase the absolute resolution of FLIC by helping to break some of the degeneracy inherent to interference imaging techniques.…”

Section: Imaging Techniquesmentioning

confidence: 99%

See 1 more Smart Citation

Molecular Organization and Signal Transduction at Intermembrane Junctions

2005

Angew Chem Int Ed

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Surfaces create an environment in which multiple forces conspire together to yield a wealth of complex chemical processes. This is especially true of cell membranes, whose fluidity and flexibility enables responsive feedback with surface chemical interactions in ways not generally seen with inorganic materials. Spatial pattern formation of cell-surface proteins at intermembrane junctions provides many beautiful examples of these phenomena, and is also emerging as a functional aspect of intercellular signaling. Correspondingly, the study of interactions of cell-membrane surfaces is attracting significant attention from cell biologists and physical chemists alike. This convergence is fueled be recent, exquisite observations of protein pattern formation events within living immunological synapses along with parallel advances in membrane reconstitution, manipulation, and imaging technologies.

“…Ein dritter Typ von Membrankontaktstellen kann durch das Zerreißen von unilamellaren Riesenvesikeln auf trägergestützten Membranen hergestellt werden. Diese Methode liefert planare Kontaktstellen mit einer typischen Größe von 10–50 μm in unterschiedlichen Adhäsionszuständen, die gut für eine Bilderzeugung mithilfe von optischen und Rastersondenverfahren geeignet sind 112–115. Diese Art von Kontaktstellen hat sich auch als nützlich für die Untersuchung membranvermittelter Reorganisation von Proteinen hin zu geordneten Zuständen erwiesen23 und wird in Abschnitt 4.2 im Zusammenhang mit der Abbildung der Membrantopographie diskutiert.…”

Section: Experimentelle Modellsystemeunclassified

Molekulare Organisation und Signaltransduktion an Kontaktstellen zwischen Membranen

2005

Angewandte Chemie

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Oberflächen schaffen eine Umgebung, in der zahlreiche Kräfte zusammenwirken und dabei eine Vielzahl komplexer chemischer Prozesse auslösen. Dies gilt vor allem für Zellmembranen, deren Fluidität und Flexibilität eine Antwort auf chemische Wechselwirkungen an der Oberfläche ermöglichen, wie man sie bei anorganischen Materialien in dieser Form nicht findet. Die Bildung räumlicher Proteinmuster an Membranoberflächen im Bereich von Membrankontaktstellen liefert viele Beispiele für solche Phänomene und spielt darüber hinaus eine wichtige Rolle bei der interzellulären Signaltransduktion. Entsprechend interessieren sich sowohl Physikochemiker als auch Zellbiologen für Wechselwirkungen an Membranoberflächen. Aktuelle, fachübergreifende Untersuchungen zur Bildung von Proteinmustern in immunologischen Synapsen und zur Rekonstitution und Manipulation von Membranen unter Verwendung moderner bildgebender Verfahren werden in diesem Aufsatz vorgestellt.