Grant: Operating Grant

Human cells contain a variety of compartments with specialized functions. Some like the nucleus store genetic information while others generate energy. This application concerns a set of such compartments implicated in the modification, sorting and delivery of various cargoes both within the cell, as well as to and from the cell surface. Carriers that often appear as small spheres, or vesicles, move important cargoes with great precision between these various compartments. The Golgi, like a hub or airport, lies at the center of this network and acts as a central sorting station. Nearly a third of proteins encoded by the human genome must pass through this hub for important modification and sorting to their ultimate destination. Therefore, mutations that compromise this process often cause disease or are sometimes lethal. Furthermore, many human pathogens hijack this pathway to ensure successful infection. Formation of carrier vesicles is mediated by the recruitment of proteins that form coats on flat membranes and facilitate their deformation into vesicles. A group of proteins called Arfs control assembly of these coats (the ground crew at the airport), while GEF proteins activate Arfs and regulate this process (air traffic controllers). Together, these proteins provide the necessary regulatory mechanism required for protein traffic and maintenance of the Golgi. While much research has focused on the Golgi, many aspects of how Arfs and GEFs perform their central roles remains unclear. Here we propose to identify the specific function of several type of Arfs and GEFs to better define their unique contribution to protein traffic. Our approach to tease these complex pathways apart relies heavily on microscopy and expression of fluorescent proteins in animal cells. Using live cell imaging we examine how each of these proteins is recruited to unique sites of action and thereby maintains the intricate organization/function of the Golgi and associated compartments.