A novel analysis of single particle trajectories quantifies the dynamic interactions between LFA-1 and the actin cytoskeleton (94.13)

Abstract

Abstract Dynamics of cell-surface proteins are strongly influenced by their localized interactions with cytoskeletal attachments or intracellular signaling molecules. We developed a technique to analyze single particle trajectories to quantify these interactions. We modeled trajectories of a cell membrane-associated protein interacting with a homogeneously distributed binding partner, and applied this model to analyze the motion of the integrin receptor LFA-1 on the surface of T cells. Our analysis reveals that the diffusion of LFA-1 is two-state, with distinct diffusion coefficients in its free and cytoskeleton-bound forms. We also quantify the rates of transition between the two states, and we show that cellular activation leads to large changes in the LFA-1-cytoskeleton interactions.