期刊
JOURNAL OF CELL BIOLOGY
卷 163, 期 2, 页码 237-243出版社
ROCKEFELLER UNIV PRESS
DOI: 10.1083/jcb.200305007
关键词
endosome; ubiquitin; multivesicular body; endosome; lysosome
类别
资金
- NIGMS NIH HHS [R01 GM046869, GM58202, GM46869, R01 GM058202] Funding Source: Medline
Ubiquitin (Ub) attachment to cell surface proteins causes their lysosomal degradation by incorporating them into lumenal membranes of multivesicular bodies (MVBs). Two yeast endosomal protein complexes have been proposed as Ub-sorting receptors, the Vps27-Hse1 complex and the ESCRT-1 complex. We used NMR spectroscopy and mutagenesis studies to map the Ub-binding surface for Vps27 and Vps23. Mutations in Ub that ablate only Vps27 binding or Vps23 binding blocked the ability of Ub to serve as an MVB sorting signal, supporting the idea that both the Vps27-Hse1 and ESCRT-1 complexes interact with ubiquitinated cargo. Vps27 also bound Vps23 directly via two PSDP motifs present within the Vps27 COOH terminus. Loss of Vps27-Vps23 association led to less efficient sorting into the endosomal lumen. However, sorting of vacuolar proteases or the overall biogenesis of the MVB were not grossly affected. In contrast, disrupting interaction between Vps27 and Hse1 caused severe defects in carboxy peptidase Y sorting and MVB formation. These results indicate that both Ub-sorting complexes are coupled for efficient recognition of ubiquitinated cargo.
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