Structural Analysis of Calreticulin, an Endoplasmic Reticulum-Resident Molecular Chaperone

Gunnar Houen*, Peter Højrup, Evaldas Ciplys, Christine Gaboriaud, Rimantas Slibinskas

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingBook chapterResearchpeer-review


Calreticulin (Calr) is an endoplasmic reticulum (ER) chaperone involved in protein quality control, Ca2+ regulation and other cellular processes. The structure of Calr is unusual, reflecting different functions of the protein: a proline-rich β-hairpin arm and an acidic C-terminal tail protrude from a globular core, composed of a β-sheet sandwich and an α-helix. The arm and tail interact in the presence of Ca2+ and cover the upper β-sheet, where a carbohydrate-binding site gives the chaperone glycoprotein affinity. At the edge of the carbohydrate-binding site is a conserved, strained disulphide bridge, formed between C106 and C137 of human Calr, which lies in a polypeptide-binding site. The lower β-sheet has several conserved residues, comprised of a characteristic triad, D166-H170-D187, Tyr172 and the free C163. In addition to its role in the ER, Calr translocates to the cell surface upon stress and functions as an immune surveillance marker. In some myeloproliferative neoplasms, the acidic Ca2+-binding C-terminal tail is transformed into a polybasic sequence.

Original languageEnglish
Title of host publicationCellular Biology of the Endoplasmic Reticulum
EditorsLuis B. Agellon, Marek Michalak
Number of pages13
Publication date2021
ISBN (Print)978-3-030-67698-8, 978-3-030-67695-7
ISBN (Electronic)978-3-030-67696-4
Publication statusPublished - 2021
SeriesProgress in molecular and subcellular biology


  • Calnexin
  • Calreticulin
  • Chaperone
  • Lectin
  • Protein stability
  • Protein structure
  • Protein synthesis


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