Dynamics of Translocons Complexes and Differentiation of the ER

New York University Medical Center, New York NY

Investigators

Abstract

Lateral mobility of membrane proteins and their differentiation into functionally distinct subdomains is very poorly understood. This project focuses on the assembly, functional organization, and dynamics of the translocon complex (TC) in the endoplasmic reticulum (ER) and how these features contribute to the function, morphological appearance of the organelle, and differentiation into rough and smooth ER domains. The TC consists of Sec61p, the translocation channel itself, and associated integral and peripheral membrane proteins that function in translocation or co-translational modifications of proteins made on membrane-bound polysomes. The hypothesis to be tested is that TCs form higher order structures that define the rough domain of the ER. These structures may be stabilized by mRNAs that interconnect TCs forming membrane bound polysomes, cytoskeletal elements, and/or hypothetical proteins that form links between the TCs. Proposed experiments will determine whether the restrained lateral mobility of GFP-tagged TCs is caused by interactions of cytoskeletal elements with the TCs and/or with membrane-bound ribosomes. The effects of ER membrane proteins p180 and CLIMP-63 on the lateral mobility of the TCs will be assessed. The PI will also investigate whether changes in the morphology of the rough ER are associated with changes in the lateral mobility of the TCs and with the expression of specific linker proteins. Additional experiments will determine whether the reorganization of the rough ER is accompanied by changes in the expression level of rough ER proteins and whether the respective RNAi molecules can suppress this rough ER reorganization.