Abstract
Sorting of ubiquitinated endosomal membrane proteins into the MVB pathway is executed by the class E Vps protein complexes ESCRT-I, -II, and -III, and the AAA-type ATPase Vps4. This study characterizes ESCRT-II, a soluble approximately 155 kDa protein complex formed by the class E Vps proteins Vps22, Vps25, and Vps36. This protein complex transiently associates with the endosomal membrane and thereby initiates the formation of ESCRT-III, a membrane-associated protein complex that functions immediately downstream of ESCRT-II during sorting of MVB cargo. ESCRT-II in turn functions downstream of ESCRT-I, a protein complex that binds to ubiquitinated endosomal cargo. We propose that the ESCRT complexes perform a coordinated cascade of events to select and sort MVB cargoes for delivery to the lumen of the vacuole/lysosome.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Carrier Proteins / metabolism*
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Carrier Proteins / ultrastructure
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Cell Membrane / metabolism*
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Cell Membrane / ultrastructure
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Endosomes / metabolism*
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Endosomes / ultrastructure
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Eukaryotic Cells / metabolism*
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Eukaryotic Cells / ultrastructure
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Fungal Proteins / metabolism*
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Fungal Proteins / ultrastructure
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Lysosomes / metabolism
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Lysosomes / ultrastructure
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Macromolecular Substances
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Membrane Proteins / genetics
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Membrane Proteins / isolation & purification
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Protein Binding / genetics
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Protein Transport / physiology*
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Saccharomyces cerevisiae
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Saccharomyces cerevisiae Proteins / genetics
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Saccharomyces cerevisiae Proteins / isolation & purification
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Transport Vesicles / metabolism*
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Transport Vesicles / ultrastructure
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Ubiquitin / genetics
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Ubiquitin / metabolism
Substances
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Carrier Proteins
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Fungal Proteins
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Macromolecular Substances
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Membrane Proteins
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Saccharomyces cerevisiae Proteins
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Ubiquitin