@article {713, title = {Active remodeling of cortical actin regulates spatiotemporal organization of cell surface molecules.}, journal = {Cell}, volume = {149}, year = {2012}, month = {2012 Jun 08}, pages = {1353-67}, abstract = {

Many lipid-tethered proteins and glycolipids exist as monomers and nanoclusters on the surface of living cells. The spatial distribution and dynamics of formation and breakup of nanoclusters does not reflect thermal and chemical equilibrium and is controlled by active remodeling of the underlying cortical actin. We propose a model for nanoclustering based on active hydrodynamics, wherein cell surface molecules bound to dynamic actin are actively driven to form transient clusters. This consistently explains all of our experimental observations. Using FCS and TIRF microscopy, we provide evidence for the existence of short, dynamic, polymerizing actin filaments at the cortex, a key assumption of the theoretical framework. Our theory predicts that lipid-anchored proteins that interact with dynamic actin must exhibit anomalous concentration fluctuations, and a cell membrane protein capable of binding directly to actin can form nanoclusters. These we confirm experimentally, providing an active mechanism for molecular organization and its spatiotemporal regulation on the plasma membrane.

}, keywords = {Actins, Animals, Cell Line, Tumor, Cell Membrane, CHO Cells, Cricetinae, Cytoskeleton, Humans, Membrane Proteins, Models, Biological, Spectrometry, Fluorescence}, issn = {1097-4172}, doi = {10.1016/j.cell.2012.05.008}, author = {Gowrishankar, Kripa and Ghosh, Subhasri and Saha, Suvrajit and C, Rumamol and Mayor, Satyajit and Rao, Madan} } @article {715, title = {Dynamic imaging of homo-FRET in live cells by fluorescence anisotropy microscopy.}, journal = {Methods Enzymol}, volume = {505}, year = {2012}, month = {2012}, pages = {291-327}, abstract = {

Multiple lipid and protein components of the plasma membrane of a living cell are organized, both compositionally and functionally, at different spatial and temporal scales. For instance, Rab protein domains in membranes the clathrin-coated pit, or the immunological synapse are exquisite examples of functional compartmentalization in cell membranes. These assemblies consist in part of nanoscale complexes of lipids and proteins and are necessary to facilitate some specific sorting and signaling functions. It is evident that cellular functions require a regulated spatiotemporal organization of components at the nanoscale, often comprising of countable number of molecular species. Here, we describe multiple homo-FRET-based imaging methods that provide information about nanoscale interactions between fluorescently tagged molecules in live cells, at optically resolved spatial resolution.

}, keywords = {Animals, Cell Membrane, Cell Tracking, Drosophila, Fluorescence Polarization, Fluorescence Resonance Energy Transfer, Green Fluorescent Proteins, Image Processing, Computer-Assisted, Lipid Metabolism, Microscopy, Confocal, Microscopy, Fluorescence}, issn = {1557-7988}, doi = {10.1016/B978-0-12-388448-0.00024-3}, author = {Ghosh, Subhasri and Saha, Suvrajit and Goswami, Debanjan and Bilgrami, Sameera and Mayor, Satyajit} }