Study membrane protein dynamics by advanced microscopic techniques

Dr Jianying Yang (MPI of Immunobiology and Epigenetics Freiburg)

Many membrane proteins are now found to exist as pre-organized nano-size protein islands in contrast to being randomly distributed in their resting stage. To better understand the function of membrane proteins based on this novel concept, a profound knowledge of the dynamics and regulation of these nano-size protein islands formation is of great interest.

For this purpose, we will use the B cell receptor, which we recenly found to form auto-inhibitory oligomers on the surface of resting B cells, as a model system to study the formation and interactions of protein islands during protein synthesis. We will establish methods with a combination of Photoactivated Localization Microscopy (PALM), Fluorescence Correlation Spectroscopy (FCS), and single molecule subunit counting by photobleaching to quantitatively characterizing the structural parameters (size, amounts, pattern, etc.) of BCR oligomers. Then, by regulating the expression of different classes of BCRs and their co-receptors using a novel riboswitch-based controlled gene expression system, we will investigate the kinetics of BCR oligomers formation and the effects of their interacting partners, such as other class of BCR or co-receptors, in this process. Additionally, we will also characterize the structural changes of BCR oligomers upon antigen or antibody simulation.