| Popis: |
During Clathrin-mediated endocytosis (CME), over 50 different proteins assemble on the plasma membrane to reshape it into a cargo-laden vesicle. Studies of Saccharomyces cerevisiae have traced a detailed timeline of assembly of the CME machinery. Assembly of this machinery is subject to regulation to ensure cargo capture; however, which CME steps are regulated, and which steps are deterministic, is unknown. In this study, we quantitatively and spatially describe progression through the CME pathway. We pinpoint a regulatory transition point that governs progression from the initiation phase of CME to the internalization phase. Availability of endocytic cargo influences maturation through this transition point, indicating that it is a cargo checkpoint. While previous studies in yeast and mammalian cells suggested that cargo ensures its own internalization through regulating CME initiation rates or frequency of abortive events, our data instead identify maturation through a checkpoint in the pathway as the cargo-sensitive step. |
