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Electrical properties of plasma membrane modulate subcellular distribution of K‐Ras
Author(s) -
Gomez Guillermo A.,
Daniotti Jose L.
Publication year - 2007
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2007.05758.x
Subject(s) - membrane , biophysics , cytoplasm , chemistry , subcellular localization , endosome , transmembrane protein , biochemistry , microbiology and biotechnology , cell membrane , intracellular , biology , receptor
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 farnesylated 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 that modify transmembrane potential caused a redistribution of K‐Ras to cytoplasm and endomembranes. Ca 2+ ionophores, compared to K + ionophores, caused a much broader redistribution of K‐Ras to endomembranes. Taken together, these results reveal the dynamic nature of interactions between K‐Ras and cellular membranes, and indicate that subcellular distribution of K‐Ras is driven by electrostatic interaction of the polybasic region of the protein with negatively charged membranes.