Clathrin is Important for Normal Actin Dynamics and Progression of Sla2p‐Containing Patches During Endocytosis in Yeast

Clathrin is a major vesicle coat protein involved in receptor‐mediated endocytosis. In yeast and higher eukaryotes, clathrin is recruited to the plasma membrane during the early stage of endocytosis along with clathrin‐associated adaptors. As coated pits undergo maturation, a burst of actin polymerization accompanies and helps drive vesicle internalization. Here, we investigate the dynamics of clathrin relative to the early endocytic patch protein Sla2p. We find that clathrin is recruited to the cortex prior to Sla2p. In the absence of clathrin, normal numbers of Sla2p patches form, but many do not internalize or are dramatically delayed in completion of endocytosis. Patches that do internalize receive Sla1p late, which is followed by Abp1, which appears near the end of Sla2p lifetime. In addition, clathrin mutants develop actin comet tails, suggesting an important function in actin patch organization/dynamics. Similar to its mammalian counterparts, the light chain (LC) subunit of yeast clathrin interacts directly with the coiled‐coil domain of Sla2p. A mutant of Sla2p that no longer interacts with LC (sla2Δ376‐573) results in delayed progression of endocytic patches and aberrant actin dynamics. These data demonstrate an important role for clathrin in organization and progression of early endocytic patches to the late stages of endocytosis.