Genetic Analysis of Yeast Sec24p Mutants Suggests Cargo Binding Is Not Co-operative during ER Export

Roy Buchanan, Andrew Kaufman, Leslie Kung-Tran, E.A. Miller (Lead / Corresponding author)

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)
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Abstract

Many eukaryotic secretory proteins are selected forexport from the endoplasmic reticulum (ER) through theirinteraction with the Sec24p subunit of the coat protein II(COPII) coat. Three distinct cargo-binding sites on yeastSec24p have been described by biochemical, genetic andstructural studies. Each site recognizes a limited set ofpeptide motifs or a folded structural domain, however,the breadth of cargo recognized by a given site and thedynamics of cargo engagement remain poorly under-stood. We aimed to gain further insight into the broadermolecular function of one of these cargo-binding sitesusing a non-biased genetic approach. We exploited thein vivolethality associated with mutation of the Sec24pB-site to identify genes that suppress this phenotypewhen overexpressed. We identifiedSMY2as a gen-eral suppressor that rescued multiple defects in Sec24p,andSEC22as a specific suppressor of two adjacentcargo-binding sites, raising the possibility of allostericregulation of these domains. We generated a novel setof mutations in Sec24p thatdistinguish these two sitesand examined the ability of Sec22p to rescue these muta-tions. Our findings suggest that co-operativity does notinfluence cargo capture at these sites, and that Sec22prescue occurs via its function as a retrograde SNARE.
Original languageEnglish
Pages (from-to)1034-1043
Number of pages10
JournalTraffic
Volume11
Issue number8
Early online date27 May 2010
DOIs
Publication statusPublished - Aug 2010

Keywords

  • cargo selection
  • COPII vesicles
  • ER export
  • intracellular traffic
  • Sec24

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