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Sna 3 Is an Rsp 5 Adaptor Protein that Relies on Ubiquitination for Its MVB Sorting
Author(s) -
MacDonald Chris,
Stringer Daniel K.,
Piper Robert C.
Publication year - 2012
Publication title -
traffic
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.677
H-Index - 130
eISSN - 1600-0854
pISSN - 1398-9219
DOI - 10.1111/j.1600-0854.2011.01326.x
Subject(s) - ubiquitin , microbiology and biotechnology , signal transducing adaptor protein , ubiquitin ligase , biology , vacuole , protein targeting , transport protein , membrane protein , protein sorting signals , ubiquitin protein ligases , integral membrane protein , biochemistry , signal transduction , membrane , peptide sequence , gene , signal peptide , cytoplasm
The process in which ubiquitin ( Ub ) conjugation is required for trafficking of integral membrane proteins into multivesicular bodies ( MVBs ) and eventual degradation in the lumen of lysosomes/vacuoles is well defined. However , Ub ‐independent pathways into MVBs are less understood. To better understand this process, we have further characterized the membrane protein Sna 3, the prototypical Ub ‐independent cargo protein sorted through the MVB pathway in yeast. We show that Sna 3 trafficking to the vacuole is critically dependent on Rsp 5 ligase activity and ubiquitination. We find Sna 3 undergoes Ub ‐dependent MVB sorting by either becoming ubiquitinated itself or associating with other ubiquitinated membrane protein substrates. In addition, our functional studies support a role for Sna 3 as an adaptor protein that recruits Rsp 5 to cargo such as the methionine transporter Mup 1, resulting in efficient Mup 1 delivery to the vacuole .