UC Berkeley

Clathrin-mediated endocytosis (CME) is the process by which plasma membrane and external material are internalized into the cell. This thesis focuses on Ede1, one of the earliest proteins recruited to endocytic sites, to gain insights into the mechanism of site initiation. In S. cerevisiae, approximately 60 proteins arrive at plasma membrane (PM) punctae to build and internalize an endocytic vesicle. This process, which occurs in just 1-2 minutes, can be divided into two phases corresponding to the arrival of the early phase proteins and the arrival of the late phase proteins. While the late phase proteins are responsible for internalizing the budding vesicle, the early phase proteins are required to position the late phase machinery on the plasma membrane. Ede1 is a scaffolding protein involved in site initiation and stabilization during the early phase. Deletion of EDE1 results in fewer site initiations and defects in the timing of vesicle maturation. Here, I dissect the functions of Ede1 to better understand how different domains contribute to its own localization, as well as endocytic site initiation and maturation. We also identify human Eps15 as an Ede1 functional homolog. When expressed in yeast, human Eps15 is recruited to endocytic sites and supports recruitment of yeast coat proteins to those sites. Future studies in human cells will to determine the extent of functional crossover between yeast Ede1 and mammalian Eps15 during endocytosis.