title: Dynamic spectrin/ankyrin-G microdomains promote lateral membrane assembly by opposing endocytosis.
abstract: Current physical models for plasma membranes emphasize dynamic 10- to 300-nm compartments at thermodynamic equilibrium but subject to thermal fluctuations. However, epithelial lateral membranes contain micrometer-sized domains defined by an underlying membrane skeleton composed of spectrin and its partner ankyrin-G. We demonstrate that these spectrin/ankyrin-G domains exhibit local microtubule-dependent movement on a time scale of minutes and encounter most of the lateral membranes within an hour. Spectrin/ankyrin-G domains exclude clathrin and clathrin-dependent cargo, and inhibit both receptor-mediated and bulk endocytosis. Moreover, inhibition of endocytosis fully restores lateral membrane height in spectrin- or ankyrin-G-depleted cells. These findings support a non-equilibrium cellular-scale model for epithelial lateral membranes, where spectrin/ankyrin-G domains actively patrol the plasma membrane, analogous to "window washers," and promote columnar morphology by blocking membrane uptake.
authors.affiliation: Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: Paul M
authors.initials: PM
authors.lastname: Jenkins
authors.affiliation: Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: Meng
authors.initials: M
authors.lastname: He
authors.affiliation: Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA ; Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA ; Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA ; Howard Hughes Medical Institute, Durham, NC 27710, USA.
authors.forename: Vann
authors.initials: V
authors.lastname: Bennett