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Sna3 Is an Rsp5 Adaptor Protein that Relies on Ubiquitination for Its MVB Sorting
Journal article   Open access

Sna3 Is an Rsp5 Adaptor Protein that Relies on Ubiquitination for Its MVB Sorting

Chris MacDonald, Daniel K. Stringer and Robert C. Piper
Traffic (Copenhagen, Denmark), Vol.13(4), pp.586-598
04/01/2012
DOI: 10.1111/j.1600-0854.2011.01326.x
PMCID: PMC3336005
PMID: 22212814
url
https://doi.org/10.1111/j.1600-0854.2011.01326.xView
Published (Version of record) Open Access

Abstract

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 Sna3, the prototypical Ub-independent cargo protein sorted through the MVB pathway in yeast. We show that Sna3 trafficking to the vacuole is critically dependent on Rsp5 ligase activity and ubiquitination. We find Sna3 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 Sna3 as an adaptor protein that recruits Rsp5 to cargo such as the methionine transporter Mup1, resulting in efficient Mup1 delivery to the vacuole.
Cell Biology Life Sciences & Biomedicine Science & Technology

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