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PubMed · 7527558

Amino-terminal basic residues of Src mediate membrane binding through electrostatic interaction with acidic phospholipids.

C T Sigal·W Zhou·C A Buser·S McLaughlin·M D Resh
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Abstract

Membrane targeting of pp60src (Src) is mediated by its myristoylated amino terminus. We demonstrate that, in addition to myristate, six basic residues in the amino terminus are essential for high-affinity binding to the lipid bilayer via electrostatic interaction with acidic phospholipids. Specifically, c-Src was shown to bind 2500-fold more strongly to vesicles composed of the physiological ratio of 2:1 phosphatidylcholine (PC)/phosphatidylserine (PS) than to neutral PC bilayer vesicles. The apparent Kd for binding of c-Src to the PC/PS bilayer was 6 x 10(-7) M. This interaction is sufficiently strong to account for c-Src membrane targeting. Mutants of c-Src in which the amino-terminal basic residues were replaced by neutral asparagine residues exhibited binding isotherms approaching that of wild-type binding to neutral bilayers (apparent Kd of 2 x 10(-3) M). The transforming v-Src and activated c-Src (Y527F) proteins also bound more strongly to PC/PS bilayers (apparent Kd of approximately 1 x 10(-5) M) than to neutral PC bilayers. In vivo experiments with Src mutants confirmed the role of positive charge in mediating membrane binding and cellular transformation.

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3T3 CellsAmino Acid SequenceAnimalsBinding SitesBinding, CompetitiveElectrochemistryKineticsLipid BilayersMiceMolecular Sequence DataMutagenesis, Site-DirectedOligopeptidesOncogene Protein pp60(v-src)PhospholipidsPoint MutationProto-Oncogene Proteins pp60(c-src)Recombinant ProteinsStructure-Activity RelationshipTransfectionComparative StudyJournal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Research Support, U.S. Gov't, P.H.S.

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C T Sigal, W Zhou, C A Buser, S McLaughlin, M D Resh. 1994-12-06. Amino-terminal basic residues of Src mediate membrane binding through electrostatic interaction with acidic phospholipids.. https://doi.org/10.1073/pnas.91.25.12253

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