Inward tubulation of the plasma membrane expedites membrane exchange and receptor presentation

Abstract

AbstractThe plasma membrane is a crucial barrier between the cell and its external environment, and it also enables efficient passage of materials and information. Membrane vesicle trafficking allows precise delivery of materials but is rather inefficient. The mechanism for efficient membrane exchange remains elusive. Here we describe inward tubulation of the plasma membrane (PM tubes) that extends deep into the cytoplasm. These widespread PM tubes elongate along microtubules and are stabilized by actin filaments and cholesterol. PM tubes are preferred sites for connection between the endoplasmic reticulum and the plasma membrane. PM tubes facilitate receptor presentation at the surface of cells, possibly also shortening the distance for transported cargo to reach the external environment.In BriefA new type of tubular membrane structures was discovered in cells, revealing a shortcut that cells employ to expedite material exchange with their external environment.HighlightsInward tubulation of the plasma membrane (PM tubes), transiently interacts with the Golgi apparatusMicrotubule side-binding proteins pull PM tubes, while actin filaments and cholesterol stabilize PM tubesPM tubes are preferred sites where ER-PM contacts form in response to increased cytoplasmic calcium concentrationPM tubes are preferred sites for the surface presentation of GLUT1 upon glucose deprivation