DESCRIPTION: Dr. Howell proposes to characterize proteins required for exocytic vesicle budding from the trans-Goli network (TGN) and to dissect their function in the steps of the budding process: recruitment of coat components to the TGN membrane, budding and uncoating of the vesicles. Her hypothesis is that the coat structure used in exocytic vesicle budding from the TGN is the lace-like TGNC, and that p62 and p200 will be components of this coat. Specific Aim 1 is biochemical dissection of the p62 complex and p200 function in exocytic vesicle budding in vitro and in vivo. Specific Aim 2 is molecular analysis of p62 and p200. Specific Aim 3 is defining the exocytic vesicle coat structure. Specific Aim 4 is identification of additional components required for TGN vesicle budding.