title: Membrane tension and peripheral protein density mediate membrane shape transitions.
abstract: Endocytosis is a ubiquitous eukaryotic membrane budding, vesiculation and internalization process fulfilling numerous roles including compensation of membrane area increase after bursts of exocytosis. The mechanism of the coupling between these two processes to enable homeostasis is not well understood. Recently, an ultrafast endocytosis (UFE) pathway was revealed with a speed significantly exceeding classical clathrin-mediated endocytosis (CME). Membrane tension reduction is a potential mechanism by which endocytosis can be rapidly activated at remote sites. Here, we provide experimental evidence for a mechanism whereby membrane tension reduction initiates membrane budding and tubulation mediated by endocytic proteins, such as endophilin A1. We find that shape instabilities occur at well-defined membrane tensions and surface densities of endophilin. From our data, we obtain a membrane shape stability diagram that shows remarkable consistency with a quantitative model. This model applies to all laterally diffusive curvature-coupling proteins and therefore a wide range of endocytic proteins.
authors.affiliation: Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Shi
authors.affiliation: Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Tobias
authors.initials: T
authors.lastname: Baumgart
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D001696:Biomechanical Phenomena; D001703:Biophysics; D002462:Cell Membrane / Q000502:physiology*; D048430:Cell Shape / Q000502:physiology; D004705:Endocytosis / Q000502:physiology*; D005089:Exocytosis / Q000502:physiology*; D008856:Microscopy, Fluorescence; D008954:Models, Biological
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C504641:endophilin A1 protein, mouse