KRAS4b, which is frequently mutated in pancreatic, colon and lung cancers, is processed in several enzymatic steps that results in the addition of a farnesyl and a methyl group to the terminal cysteine residue. Plasma membrane localization of KRAS4b requires this processing along with a polybasic stretch of lysines within the hypervariable region. KRAS4b can bind to RAF-RBD in solution but membrane bound KRAS4b is required for RAF-kinase activation. In order to determine why membrane interaction of KRAS4b is required for MAPK signal transduction we under took a structural and biochemical analysis of KRAS4b-membrane interactions. We have developed methods using an engineered baculovirus for the insect cell production of farnesylated and methylated KRAS4b (KRAS4b-FME) and this material was used in these studies. We have demonstrated that the stable interaction of KRAS4b-FME to lipid Nanodiscs and tethered lipid bilayers is dependent on the presence of anionic phospholipids. Using analytical ultracentrifugation we have evaluated the binding stoichiometry of KRAS4b-FME with Nanodiscs. In addition we have used neutron reflectivity to determine the orientation of KRAS4b-FME on tethered lipid bilayers.

Citation Format: Que Van, William K. Gillette, Dominic Esposito, Rodolfo Ghirlando, Frank Heinrich, Andrew G. Stephen. Structural and biochemical characterization of farnesylated and methylated KRAS-membrane interactions. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1879.