Probing the dynamics of growth factor receptor by single-molecule fluorescence imaging.

Single-molecule fluorescence imaging with living cells offers a new approach to visualize and monitor individual proteins during their cellular activities. It facilities the study of cell signaling proteins whose structures and interactions are highly temporal and spatial regulated. In this review, we will mainly present our recent work on probing the dynamics of two types of important transmembrane growth factor receptors, transforming growth factor β receptors and epidermal growth factor receptors, by single-molecule fluorescence microscopy. This includes the characterization of receptor stoichiometry, monomer-dimer interconversion kinetics, effects of microenvironment on receptor membrane diffusion, and intracellular transportation under different signaling conditions. Related studies on these receptors from other groups, as well as the method developments, will be also discussed. Single-molecule study helps to achieve a better understanding of the molecular mechanism of receptor activation, endocytosis and other molecular events in transmembrane signaling.