The CORVET Subunit Vps8 Cooperates with the Rab5 Homolog Vps21 to Induce Clustering of Late Endosomal Compartments

Autor(en): Markgraf, Daniel F.
Ahnert, Franziska
Arlt, Henning 
Mari, Muriel
Peplowska, Karolina
Epp, Nadine
Griffith, Janice
Reggiori, Fulvio
Ungermann, Christian 
Stichwörter: BINDING-PROTEIN; Cell Biology; CRYOSECTIONING PROCEDURE; GUANINE-NUCLEOTIDE EXCHANGE; PREVACUOLAR COMPARTMENT; RING FINGER PROTEIN; SNARE COMPLEX; TETHERING COMPLEX; ULTRASTRUCTURAL ANALYSIS; VACUOLE FUSION; YEAST SACCHAROMYCES-CEREVISIAE
Erscheinungsdatum: 2009
Herausgeber: AMER SOC CELL BIOLOGY
Journal: MOLECULAR BIOLOGY OF THE CELL
Volumen: 20
Ausgabe: 24
Startseite: 5276
Seitenende: 5289
Zusammenfassung: 
Membrane tethering, the process of mediating the first contact between membranes destined for fusion, requires specialized multisubunit protein complexes and Rab GTPases. In the yeast endolysosomal system, the hexameric HOPS tethering complex cooperates with the Rab7 homolog Ypt7 to promote homotypic fusion at the vacuole, whereas the recently identified homologous CORVET complex acts at the level of late endosomes. Here, we have further functionally characterized the CORVET-specific subunit Vps8 and its relationship to the remaining subunits using an in vivo approach that allows the monitoring of late endosome biogenesis. In particular, our results indicate that Vps8 interacts and cooperates with the activated Rab5 homolog Vps21 to induce the clustering of late endosomal membranes, indicating that Vps8 is the effector subunit of the CORVET complex. This clustering, however, requires Vps3, Vps16, and Vps33 but not the remaining CORVET subunits. These data thus suggest that the CORVET complex is built of subunits with distinct activities and potentially, their sequential assembly could regulate tethering and successive fusion at the late endosomes.
ISSN: 10591524
DOI: 10.1091/mbc.E09-06-0521

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