The AP‐2 complex is required for proper temporal and spatial dynamics of endocytic patches in fission yeast

In metazoans the AP‐2 complex has a well‐defined role in clathrin‐mediated endocytosis. By contrast, its direct role in endocytosis in unicellular eukaryotes has been questioned. Here, we report co‐ immunoprecipitation between the fission yeast AP‐2 component Apl3p and clathrin, as well as the genetic interactions between apl3Δ and clc1 and sla2Δ/end4Δ mutants. Furthermore, a double clc1 apl3Δ mutant was found to be defective in FM4‐64 uptake. In an otherwise wild‐type strain, apl3Δ cells exhibit altered dynamics of the endocytic sites, with a heterogeneous and extended lifetime of early and late markers at the patches. Additionally, around 50% of the endocytic patches exhibit abnormal spatial dynamics, with immobile patches and patches that bounce backwards to the cell surface, showing a pervasive effect of the absence of AP‐2. These alterations in the endocytic machinery result in abnormal cell wall synthesis and morphogenesis. Our results complement those found in budding yeast and confirm that a direct role of AP‐2 in endocytosis has been conserved throughout evolution.