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I will describe both the theoretical and experimental efforts, that we developed over the last years at the Curie Institute in order to understand certain features of cellular traffic, namely the formation of phospholipid nanotubes under the action of molecular motors. Such tubes are hollow cylinders of typically 30 to 50 nanometers diameter. I will in particular show why and how such structures can be pulled out of giant unilamellar vesicles. The collective dynamics of molecular motors will be shown to be non trivial and involve dynamical transitions. The prediction of a critical motor concentration for pulling tubes is quantitatively born out by experiment without any adjustable parameter. The analysis of the motor distribution in the tube, for concentrations up to ten times the critical concentration allows for the measurement of the ÒonÓ rate in conditions close to physiological. I will further discuss some of the transitions related to lipid and protein sorting, which may occur in those tubular systems and show under which conditions the tubes may break into closed vesicles. I. DERENYI, F. JULICHER, J. PROST Formation and interactions of membrane tubes Phys. Rev. Lett, 88, 23 (2002) A. ROUX, G. CAPELLO, J. CARTAUD, J. PROST, B. GOUD, P. BASSEREAU A minimal system allowing tubulation using molecular motors pulling on giant liposomes Proc. Natl. Acad. Sci. U.S.A, 99, 5394-5399 (2002) A. ROUX, D. CUVELIER, J. PROST, P. NASSOY, P. BASSEREAU, B. GOUD Role of Curvature and Phase Transition in Lipid Sorting and Fission of Membranes Tubules The Embo journal (2005) C. LEDUC, O.CAMPAS, K. ZELDOVCH, A. ROUX, P.JOLIMAëTRE, L. BOUREL-BONNET, B. GOUD, J. JOANNY, P. BASSEREAU, J. PROST Cooperative extraction of membrane nanotubes by molecular motors Proc. Natl. Acad. Sci. U.S.A, 101, 17096-17101(2004) J.M. ALLAIN, STORM C, ROUX A, BEN AMAR M., JOANNY J.F Fission of a multiphase membrane tube Phys. Rev. Lett 93:158104 (2004) |
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