Proteins of the Ras superfamily are located at the inner leaflet of the plasma membrane and play an important role in cellular signal transduction processes, such as cell growth or differentiation. Since nanoclustering is discussed as an effective signaling mechanism, determination of the rotational and translational dynamics of membrane-associated Ras proteins may help revealing additional mechanistic information about protein clustering and interactions with effector proteins. In this study, different biophysical approaches are combined to investigate the partitioning behavior and dynamical properties of two Ras isoforms, namely N- and K-Ras, in unilamellar vesicles of varied lipid composition. As model biomembrane systems, pure fluid-like (liquid-disordered), neutral and anionic heterogeneous model raft membranes were used. Confocal laser scanning microscopy was applied to gain information on the partitioning of the Ras lipoproteins into the different model membrane systems. Fluorescence anisotropy and fluorescence correlation spectroscopy experiments were carried out to yield information on dynamical properties, such as the rotational correlation time and the translational diffusion coefficient, of the fully lipidated BODIPY-labeled Ras proteins. The results reveal a preferential incorporation of Ras into fluid-like liquid-disordered lipid domains, independent of the Ras isoform and GDP/GTP-loading [1]. Although the rotational mobility remains quite high upon membrane insertion, the translational dynamics is limited by the viscosity of the respective lipid system, in agreement with results obtained in in vivo studies. Depending on the nucleotide loading, no significant differences could be detected with respect to the dynamics upon membrane incorporation.Reference[1] Weise K, Kapoor S, Denter C, Nikolaus J, Opitz N, Koch S, Triola G, Herrmann A, Waldmann H, and Winter R (2011) J. Am. Chem. Soc. 133:880-887.