scholarly journals Ent5p Is Required with Ent3p and Vps27p for Ubiquitin-dependent Protein Sorting into the Multivesicular Body

2004 ◽  
Vol 15 (7) ◽  
pp. 3031-3041 ◽  
Author(s):  
Anne Eugster ◽  
Eve-Isabelle Pécheur ◽  
Fabrice Michel ◽  
Barbara Winsor ◽  
François Letourneur ◽  
...  
Keyword(s):  
Protein Sorting ◽  
Multivesicular Body ◽  
Yeast Protein ◽  
Enth Domain ◽  
Fyve Domain ◽  
Late Endosomes ◽  
Dependent Protein ◽  
In Cells

At the late endosomes, cargoes destined for the interior of the vacuole are sorted into invaginating vesicles of the multivesicular body. Both PtdIns(3,5)P2 and ubiquitin are necessary for proper sorting of some of these cargoes. We show that Ent5p, a yeast protein of the epsin family homologous to Ent3p, localizes to endosomes and specifically binds to PtdIns(3,5)P2 via its ENTH domain. In cells lacking Ent3p and Ent5p, ubiquitin-dependent sorting of biosynthetic and endocytic cargo into the multivesicular body is disrupted, whereas other trafficking routes to the vacuole are not affected. Ent3p and Ent5p are associated with Vps27p, a FYVE domain containing protein that interacts with ubiquitinated cargoes and is required for protein sorting into the multivesicular body. Therefore, Ent3p and Ent5p are the first proteins shown to be connectors between PtdIns(3,5)P2- and the Vps27p-ubiquitin-driven sorting machinery at the multivesicular body.

scholarly journals The ERM proteins interact with the HOPS complex to regulate the maturation of endosomes

2011 ◽  
Vol 22 (3) ◽  
pp. 375-385 ◽  
Author(s):  
Dafne Chirivino ◽  
Laurence Del Maestro ◽  
Etienne Formstecher ◽  
Philippe Hupé ◽  
Graça Raposo ◽  
...  
Keyword(s):  
Egf Receptor ◽  
Protein Sorting ◽  
Small Gtpases ◽  
Erm Proteins ◽  
Degradative Pathway ◽  
Late Endosomes ◽  
Early Endosomes ◽  
In Cells ◽  
Hops Complex

In the degradative pathway, the progression of cargos through endosomal compartments involves a series of fusion and maturation events. The HOPS (homotypic fusion and protein sorting) complex is part of the machinery that promotes the progression from early to late endosomes and lysosomes by regulating the exchange of small GTPases. We report that an interaction between subunits of the HOPS complex and the ERM (ezrin, radixin, moesin) proteins is required for the delivery of EGF receptor (EGFR) to lysosomes. Inhibiting either ERM proteins or the HOPS complex leads to the accumulation of the EGFR into early endosomes, delaying its degradation. This impairment in EGFR trafficking observed in cells depleted of ERM proteins is due to a delay in the recruitment of Rab7 on endosomes. As a consequence, the maturation of endosomes is perturbed as reflected by an accumulation of hybrid compartments positive for both early and late endosomal markers. Thus, ERM proteins represent novel regulators of the HOPS complex in the early to late endosomal maturation.

scholarly journals Ceramide chain length–dependent protein sorting into selective endoplasmic reticulum exit sites

2020 ◽  
Vol 6 (50) ◽  
pp. eaba8237
Author(s):  
Sofia Rodriguez-Gallardo ◽  
Kazuo Kurokawa ◽  
Susana Sabido-Bozo ◽  
Alejandro Cortes-Gomez ◽  
Atsuko Ikeda ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Chain Length ◽  
Secretory Pathway ◽  
Protein Sorting ◽  
Endoplasmic Reticulum Membrane ◽  
Lipid Chain ◽  
Secretory Transport ◽  
Dependent Protein ◽  
Cellular Compartmentalization

Protein sorting in the secretory pathway is crucial to maintain cellular compartmentalization and homeostasis. In addition to coat-mediated sorting, the role of lipids in driving protein sorting during secretory transport is a longstanding fundamental question that still remains unanswered. Here, we conduct 3D simultaneous multicolor high-resolution live imaging to demonstrate in vivo that newly synthesized glycosylphosphatidylinositol-anchored proteins having a very long chain ceramide lipid moiety are clustered and sorted into specialized endoplasmic reticulum exit sites that are distinct from those used by transmembrane proteins. Furthermore, we show that the chain length of ceramide in the endoplasmic reticulum membrane is critical for this sorting selectivity. Our study provides the first direct in vivo evidence for lipid chain length–based protein cargo sorting into selective export sites of the secretory pathway.

scholarly journals Human ESCRT-II Complex and Its Role in Human Immunodeficiency Virus Type 1 Release

2006 ◽  
Vol 80 (19) ◽  
pp. 9465-9480 ◽  
Author(s):  
Charles Langelier ◽  
Uta K. von Schwedler ◽  
Robert D. Fisher ◽  
Ivana De Domenico ◽  
Paul L. White ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Protein Sorting ◽  
Growth Factor Receptor ◽  
Multivesicular Body ◽  
Vesicle Formation ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT The budding of many enveloped RNA viruses, including human immunodeficiency virus type 1 (HIV-1), requires some of the same cellular machinery as vesicle formation at the multivesicular body (MVB). In Saccharomyces cerevisiae, the ESCRT-II complex performs a central role in MVB protein sorting and vesicle formation, as it is recruited by the upstream ESCRT-I complex and nucleates assembly of the downstream ESCRT-III complex. Here, we report that the three subunits of human ESCRT-II, EAP20, EAP30, and EAP45, have a number of properties in common with their yeast orthologs. Specifically, EAP45 bound ubiquitin via its N-terminal GRAM-like ubiquitin-binding in EAP45 (GLUE) domain, both EAP45 and EAP30 bound the C-terminal domain of TSG101/ESCRT-I, and EAP20 bound the N-terminal half of CHMP6/ESCRT-III. Consistent with its expected role in MVB vesicle formation, (i) human ESCRT-II localized to endosomal membranes in a VPS4-dependent fashion and (ii) depletion of EAP20/ESCRT-II and CHMP6/ESCRT-III inhibited lysosomal targeting and downregulation of the epidermal growth factor receptor, albeit to a lesser extent than depletion of TSG101/ESCRT-I. Nevertheless, HIV-1 release and infectivity were not reduced by efficient small interfering RNA depletion of EAP20/ESCRT-II or CHMP6/ESCRT-III. These observations indicate that there are probably multiple pathways for protein sorting/MVB vesicle formation in human cells and that HIV-1 does not utilize an ESCRT-II-dependent pathway to leave the cell.

γ2 and γ1AP-1 complexes: Different essential functions and regulatory mechanisms in clathrin-dependent protein sorting

2017 ◽  
Vol 96 (4) ◽  
pp. 356-368 ◽  
Author(s):  
Daniela Zizioli ◽  
Constanze Geumann ◽  
Manuel Kratzke ◽  
Ratnakar Mishra ◽  
Guiseppe Borsani ◽  
...  
Keyword(s):  
Protein Sorting ◽  
Regulatory Mechanisms ◽  
Dependent Protein

scholarly journals Skp1p Regulates Soi3p/Rav1p Association with Endosomal Membranes but Is Not Required for Vacuolar ATPase Assembly

2006 ◽  
Vol 5 (12) ◽  
pp. 2104-2113 ◽  
Author(s):  
E. J. Brace ◽  
Leah P. Parkinson ◽  
Robert S. Fuller
Keyword(s):  
Ubiquitin Ligase ◽  
Fluorescent Protein ◽  
Sole Source ◽  
Vacuolar Atpase ◽  
Cellular Functions ◽  
Yeast Protein ◽  
Late Endosomes ◽  
Endosomal Membranes ◽  
Green Fluorescent

ABSTRACT Skp1p is an essential component of SCF-type E3 ubiquitin ligase complexes and associates with these through binding to F-box proteins. Skp1p also binds F-box proteins in a number of non-SCF complexes. The Skp1p-associated yeast protein Soi3p/Rav1p (hereafter referred to as Rav1p) is a component of the RAVE complex required for regulated assembly of vacuolar ATPase (V-ATPase). Rav1p is also involved in transport of TGN proteins and endocytic cargo between early and late endosomes. To evaluate the role of Skp1p in the RAVE complex, we made use of the fact that overexpression of Rav1p is toxic because it sequesters Skp1p from essential interactions. We isolated a separation of function allele of SKP1, skp1(Asn108Tyr), that completely abrogated the Rav1p interaction but allowed Skp1p to perform other essential cellular functions. Cells containing the skp1(Asn108Tyr) allele as the sole source of Skp1p exhibited normal V-ATPase assembly and activity. However, in the skp1(Asn108Tyr) mutant strain, the membrane-associated pool of Rav1-green fluorescent protein was increased, suggesting that Skp1p is important for the release of Rav1p from endosomal membranes where it functions in V-ATPase assembly. Thus, although part of the RAVE complex, Skp1p does not appear to be involved in V-ATPase assembly but instead in the cycling of the complex off membranes. This work also provides a generalizable approach to defining the roles of interactions of Skp1p with individual F-box proteins through the isolation of special alleles of SKP1.

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