Molecular organisation of the secretory and endocytic pathways

All animal cells release proteins into and take up proteins from the surrounding fluid. They also transport proteins between internal compartments, each of which has a unique composition and a specific function. Transport out of and into cells, and between internal compartments, is crucial for the normal functioning of cells, as well as the inter-cellular communication that is essential in all animals. Defects in these transport steps are associated with many diseases. It is therefore important we understand how this transport operates at the molecular level. The aim of the work in this application is to apply the technique of high-resolution electron microscopy, combined with a variety of modern molecular approaches, to increase our understanding of a number of key transport steps. This will allow us to gain insights into how the transport pathways function in a healthy cell, and consequently how defects in particular aspects of this transport may contribute to disease.

The secretory and endocytic pathways are of fundamental importance to eukaryotic cells. The secretory pathway is responsible for the synthesis of new lipid, secretory and membrane proteins, and their subsequent delivery to the correct final destination, either inside or outside the cell. The endocytic pathway is responsible for the internalisation of proteins and their sorting to the appropriate intracellular compartment or recycling back to the cell surface. Although much progress has been made in identifying the machinery that makes these pathways function correctly, there is much we still do not understand. The focus of the four groups named in this proposal is to develop this understanding by focussing on key aspects of both pathways. The aim of this application is to provide electron microscopy support for the named research groups, allowing them to pursue a variety of related projects that rely on high-resolution analysis of protein distribution or cellular morphology. By combining electron microscopy with a number of established molecular approaches it will be possible to address specific questions that would otherwise be intractable. This work will increase our understanding of the molecular organisation of the secretory and endocytic pathways, and how defects in specific trafficking components may contribute to disease.