The Vps27p Hse1p complex binds ubiquitin and mediates endosomal protein sorting.
Membrane proteins that are degraded in the vacuole of Saccharomyces cerevisiae are sorted into discrete intralumenal vesicles, analogous to the internal membranes of multi-vesiculated bodies (MVBs). Recently, it has shown that the attachment of ubiquitin (Ub) mediates sorting into lumenal membranes. We describe a complex of Vps27p and Hse1p that localizes to endosomal compartments and is required for the recycling of Golgi proteins, formation of lumenal membranes and sorting of ubiquitinated proteins into those membranes. The Vps27p-Hse1p complex binds to Ub and requires multiple Ub Interaction Motifs (UIMs). Mutation of these motifs results in specific defects in the sorting of ubiquitinated proteins into the vacuolar lumen. However, the recycling of Golgi proteins and the generation of lumenal membranes proceeds normally in Delta UIM mutants. These data support a model in which the Vps27p-Hse1p complex has multiple functions at the endosome, one of which is as a sorting receptor for ubiquitinated membrane proteins destined for degradation.
Bilodeau
Patricia S
PS
Department of Physiology and Biophysics, 5-660 Bowen Science Building, University of Iowa, Iowa City, IA 52242, USA.
Urbanowski
Jennifer L
JL
Winistorfer
Stanley C
SC
Piper
Robert C
RC
D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D056827:Endosomal Sorting Complexes Required for Transport; D011992:Endosomes / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D025801:Ubiquitin / Q000378:metabolism*; D033921:Vesicular Transport Proteins
D002352:Carrier Proteins; D056827:Endosomal Sorting Complexes Required for Transport; C464563:Hse1 protein, S cerevisiae; D046911:Macromolecular Substances; D008565:Membrane Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D029701:Saccharomyces cerevisiae Proteins; D025801:Ubiquitin; C119627:VPS27 protein, S cerevisiae; D033921:Vesicular Transport Proteins