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Gyrating Clathrin: Highly Dynamic Clathrin Structures Involved in Rapid Receptor Recycling
Author(s) -
Zhao Yanqiu,
Keen James H.
Publication year - 2008
Publication title -
traffic
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.677
H-Index - 130
eISSN - 1600-0854
pISSN - 1398-9219
DOI - 10.1111/j.1600-0854.2008.00819.x
Subject(s) - clathrin , endosome , endocytic cycle , microbiology and biotechnology , biology , clathrin adaptor proteins , transferrin receptor , endocytosis , golgi apparatus , signal transducing adaptor protein , fluorescence recovery after photobleaching , transport protein , receptor mediated endocytosis , transferrin , receptor , intracellular , biochemistry , signal transduction , endoplasmic reticulum , membrane
We report here detection of novel intracellular clathrin‐coated structures revealed by continuous high‐speed imaging of cells expressing green fluorescent protein fusion proteins. These structures, which we operationally term ‘gyrating clathrin’ (G‐clathrin), are characterized by localized but extremely rapid movement, leading to the hypothesis that they are coated buds on waving membrane tubules. G‐clathrin structures have structurally and functionally distinct features. They lack detectable adaptor proteins AP‐1 and AP‐2 but contain GGA1 [Golgi‐localized, γ‐ear‐containing, Arf (ADP‐ribosylation factor)‐binding protein] as well as the cation‐dependent mannose‐6‐phosphate receptor. While they accumulate internalized transferrin (Tf), they do not contain detectable levels of cargos targeted for the late endosome/lysosome pathway such as EGF and dextran. Pulse‐chase studies indicate that Tf appears in G‐clathrin structures in the cell periphery after sorting endosomes (SEs), but before filling of the perinuclear endocytic recycling compartment. Furthermore, the inhibitors LY294002 and wortmannin, which inhibit direct recycling of Tf from SEs to the plasma membrane, also block its appearance in G‐clathrin. These observations suggest that peripheral G‐clathrin contributes to rapid recycling, a kinetically defined compartment that has largely eluded structural identification. More generally, the rapid continuous live cell imaging reported here reveals new aspects of membrane trafficking.