Electrostatics and the Membrane Association of Src: Theory and Experiment
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- 作者：Diana Murray ; Luz Hermida-Matsumoto ; Carolyn A. Buser ; James Tsang ; Catherine T. Sigal ; Nir Ben-Tal ; Barry Honig ; Marilyn D. Resh ; and Stuart McLaughlin
- 刊名：Biochemistry
- 出版年：1998
- 出版时间：February 24, 1998
- 年：1998
- 卷：37
- 期：8
- 页码：2145 - 2159
- 全文大小：230K
- 年卷期：v.37,no.8(February 24, 1998)
- ISSN：1520-4995
文摘
The binding of Src to phospholipid membranes requires bothhydrophobic insertion of itsmyristate into the hydrocarbon interior of the membrane and nonspecificelectrostatic interaction of itsN-terminal cluster of basic residues with acidic phospholipids. Weprovide a theoretical description ofthe electrostatic partitioning of Src onto phospholipid membranes.Specifically, we use molecular modelsto represent a nonmyristoylated peptide corresponding to residues2-19 of Src [nonmyr-Src(2-19);GSSKSKPKDPSQRRRSLE-NH2] and a phospholipid bilayer,calculate the electrostatic interaction bysolving the nonlinear Poisson-Boltzmann equation, and predict themolar partition coefficient usingstatistical thermodynamics. The theoretical predictions agree withexperimental data obtained by measuringthe partitioning of nonmyr-Src(2-19) onto phospholipidvesicles: membrane binding increases as themole percent of acidic lipid in the vesicles is increased, the ionicstrength of the solution is decreased, orthe net positive charge of the peptide is increased. Thetheoretical model also correctly predicts themeasured partitioning of the myristoylated peptide,myr-Src(2-19); for example, adding 33% acidiclipidto electrically neutral vesicles increases the partitioning ofmyr-Src(2-19) 100-fold. Phosphorylatingeither serine 12 (by protein kinase C) or serine 17 (by cAMP-dependentprotein kinase) decreases thepartitioning of myr-Src(2-19) onto vesicles containing acidiclipid 10-fold. We investigated the effectof phosphorylation on the localization of Src to biological membranesby expressing fusion constructs ofSrc's N terminus with a soluble carrier protein in COS-1 cells;phosphorylation produces a small shift inthe distribution of the Src chimeras from the plasma membrane to thecytosol.