Galectin-9 binds to O-glycans on protein disulfide isomerase

Katrin Schaefer, Nicholas E. Webb, Mabel Pang, Jenny E. Hernandez-Davies, Katharine P. Lee, Pascual Gonzalez, Martin V. Douglass, Benhur Lee, Linda G. Baum

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


Changes in the T cell surface redox environment regulate critical cell functions, such as cell migration, viral entry and cytokine production. Cell surface protein disulfide isomerase (PDI) contributes to the regulation of T cell surface redox status. Cell surface PDI can be released into the extracellular milieu or can be internalized by T cells. We have found that galectin-9, a soluble lectin expressed by T cells, endothelial cells and dendritic cells, binds to and retains PDI on the cell surface. While endogenous galectin-9 is not required for basal cell surface PDI expression, exogenous galectin-9 mediated retention of cell surface PDI shifted the disulfide/thiol equilibrium on the T cell surface. O-glycans on PDI are required for galectin-9 binding, and PDI recognition appears to be specific for galectin-9, as galectin-1 and galectin-3 do not bind PDI. Galectin-9 is widely expressed by immune and endothelial cells in inflamed tissues, suggesting that T cells would be exposed to abundant galectin-9, in cis and in trans, in infectious or autoimmune conditions.

Original languageEnglish
Pages (from-to)878-887
Number of pages10
Issue number9
StatePublished - 1 Sep 2017


  • Galectin-9
  • O-glycans
  • Protein disulfide isomerase


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