Polarized anionic phospholipids and exocytosis are implicated in the polarized recruitment of budding yeast AP180, an endocytic initiator

Abstract

Understanding of the mechanisms that initiate clathrin-mediated endocytosis (CME) is incomplete. Recent studies in budding yeast identified the endocytic adaptor proteins Yap1801/Yap1802 (budding yeast AP180) as key CME factors that promote CME initiation in daughter cells during polarized growth, but how Yap1801/2 are recruited preferentially to the plasma membrane of daughter cells is not clear. The only known cargos for Yap1801/2 in yeast are the synaptobrevins Snc1 and Snc2, which serve as v-SNARES for exocytic vesicles reaching the plasma membrane and are crucial for polarized cell growth. In this study, we examine the spatiotemporal dynamics of functional, fluorescent protein-tagged Snc2 expressed from its endogenous locus and provide evidence that, along with anionic phospholipids, Snc2 specifically recruits Yap1802 to growing daughter cells. This protein-protein interaction creates a direct link between polarized secretion and CME and has further implications in CME initiation.