Monitoring chaperone engagement of substrates in the endoplasmic reticulum of live cells

Erik L. Snapp, Ajay Sharma, Jennifer Lippincott-Schwartz, Ramanujan S. Hegde

Research output: Contribution to journalArticle

83 Scopus citations

Abstract

The folding environment in the endoplasmic reticulum (ER) depends on multiple abundant chaperones that function together to accommodate a range of substrates. The ways in which substrate engagement shapes either specific chaperone dynamics or general ER attributes in vivo remain unknown. In this study, we have evaluated how changes in substrate flux through the ER influence the diffusion of both the lectin chaperone calreticulin and an inert reporter of ER crowdedness. During acute changes in substrate load, the inert probe revealed no changes in ER organization, despite significant changes in calreticulin dynamics. By contrast, inhibition of the lectin chaperone system caused rapid changes in the ER environment that could be reversed over time by easing new substrate burden. Our findings provide insight into the normal organization and dynamics of an ER chaperone and characterize the capacity of the ER to maintain homeostasis during acute changes in chaperone activity and availability.

Original languageEnglish (US)
Pages (from-to)6536-6541
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume103
Issue number17
DOIs
StatePublished - Apr 25 2006

Keywords

  • Castanospermine
  • Fluorescence loss in photobleaching
  • Fluorescence recovery after photobleaching
  • Pactamycin
  • Puromycin

ASJC Scopus subject areas

  • General

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