Scientific article

Functional specialization of calreticulin domains

Published inThe Journal of cell biology, vol. 154, no. 5, p. 961-972
Publication date2001

Calreticulin is a Ca2+-binding chaperone in the endoplasmic reticulum (ER), and calreticulin gene knockout is embryonic lethal. Here, we used calreticulin-deficient mouse embryonic fibroblasts to examine the function of calreticulin as a regulator of Ca2+ homeostasis. In cells without calreticulin, the ER has a lower capacity for Ca2+ storage, although the free ER luminal Ca2+ concentration is unchanged. Calreticulin-deficient cells show inhibited Ca2+ release in response to bradykinin, yet they release Ca2+ upon direct activation with the inositol 1,4,5-trisphosphate (InsP3). These cells fail to produce a measurable level of InsP3 upon stimulation with bradykinin, likely because the binding of bradykinin to its cell surface receptor is impaired. Bradykinin binding and bradykinin-induced Ca2+ release are both restored by expression of full-length calreticulin and the N + P domain of the protein. Expression of the P + C domain of calreticulin does not affect bradykinin-induced Ca2+ release but restores the ER Ca2+ storage capacity. Our results indicate that calreticulin may play a role in folding of the bradykinin receptor, which affects its ability to initiate InsP3-dependent Ca2+ release in calreticulin-deficient cells. We concluded that the C domain of calreticulin plays a role in Ca2+ storage and that the N domain may participate in its chaperone functions.

  • Animals
  • Bradykinin/pharmacology
  • Calcium/ metabolism
  • Calcium Channels/genetics/metabolism
  • Calcium-Binding Proteins/genetics/ metabolism
  • Calcium-Transporting ATPases/metabolism
  • Calreticulin
  • Cell Line
  • Endoplasmic Reticulum/ metabolism
  • Enzyme Inhibitors/pharmacology
  • Fibroblasts/drug effects/physiology
  • Flow Cytometry
  • Homeostasis
  • Immunoblotting
  • Inositol 1,4,5-Trisphosphate Receptors
  • Mice
  • Mice, Knockout
  • Microscopy, Fluorescence
  • Molecular Chaperones/genetics/metabolism
  • Protein Isoforms/genetics/metabolism
  • Protein Structure, Tertiary
  • Receptors, Bradykinin/metabolism
  • Receptors, Cytoplasmic and Nuclear/genetics/metabolism
  • Ribonucleoproteins/genetics/ metabolism
  • Sarcoplasmic Reticulum Calcium-Transporting ATPases
  • Thapsigargin/pharmacology
  • Transfection
Citation (ISO format)
NAKAMURA, K. et al. Functional specialization of calreticulin domains. In: The Journal of cell biology, 2001, vol. 154, n° 5, p. 961–972. doi: 10.1083/jcb.200102073
Updates (1)
ISSN of the journal0021-9525

Technical informations

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