TAILIEUCHUNG - Báo cáo khoa học: Electrical properties of plasma membrane modulate subcellular distribution of K-Ras

K-Ras is a small G-protein, localized mainly at the inner leaflet of the plasma membrane. The membrane targeting signal of this protein consists of a polybasic C-terminal sequence of six contiguous lysines and a farnesyl-ated cysteine. Results from biophysical studies in model systems suggest that hydrophobic and electrostatic interactions are responsible for the membrane binding properties of K-Ras. | ễFEBS Journal Electrical properties of plasma membrane modulate subcellular distribution of K-Ras Guillermo A. Gomez and Jose L. Daniotti Centro de Investigaciones en Quimica Biologica de Cordoba CIQUIBIC UNC-CONICET Departamento de Quimica Biologica Universidad Nacionalde Cordoba Argentina Keywords calcium membrane potential polyphosphoinositides RAS sialic acid Correspondence J. L. Daniotti Centro de Investigaciones en Quimica Biologica de Cordoba CIQUIBIC UNC-CONICET Departamento de Quimica Biologica Facultad de Ciencias Quimicas Universidad Nacionalde Cordoba Haya de la Torre y Medina Allende Ciudad Universitaria X5000HUA Cordoba Argentina Fax 54 351 4334074 Tel 54 351 4334168 4171 E-mail daniotti@ Received 28 November 2006 revised 16 February 2007 accepted 27 February 2007 doi K-Ras is a small G-protein localized mainly at the inner leaflet of the plasma membrane. The membrane targeting signal of this protein consists of a polybasic C-terminal sequence of six contiguous lysines and a farnesyl-ated cysteine. Results from biophysical studies in model systems suggest that hydrophobic and electrostatic interactions are responsible for the membrane binding properties of K-Ras. To test this hypothesis in a cellular system we first evaluated in vitro the effect of electrolytes on K-Ras membrane binding properties. Results demonstrated the electrical and reversible nature of K-Ras binding to anionic lipids in membranes. We next investigated membrane binding and subcellular distribution of K-Ras after disruption of the electrical properties of the outer and inner leaflets of plasma membrane and ionic gradients through it. Removal of sialic acid from the outer plasma membrane caused a redistribution of K-Ras to recycling endosomes. Inhibition of polyphosphoinositide synthesis at the plasma membrane by depletion of cellular ATP resulted in a similar subcellular redistribution of K-Ras. Treatment of cells with ionophores

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