Cutting edge: Tapasin is retained in the endoplasmic reticulum by dynamic clustering and exclusion from endoplasmic reticulum exit sites

Tsvetelina Pentcheva, Elias T. Spiliotis, Michael Edidin

Research output: Contribution to journalArticlepeer-review

Abstract

Tapasin retains empty or suboptimally loaded MHC class I molecules in the endoplasmic reticulum (ER). However, the molecular mechanism of this process and how tapasin itself is retained in the ER are unknown. These questions were addressed by tagging tapasin with the cyan fluorescent protein or yellow fluorescent protein (YFP) and probing the distribution and mobility of the tagged proteins. YFP-tapasin molecules were functional and could be isolated in association with TAP, as reported for native tapasin. YFP-tapasin was excluded from ER exit sites even after accumulation of secretory cargo due to disrupted anterograde traffic. Almost all tapasin molecules were clustered, and these clusters diffused freely in the ER. Tapasin oligomers appear to be retained by the failure of the export machinery to recognize them as cargo.

Original languageEnglish (US)
Pages (from-to)1538-1541
Number of pages4
JournalJournal of Immunology
Volume168
Issue number4
DOIs
StatePublished - Feb 15 2002

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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