Calreticulin/calnexin (IPR001580)

Short name: Calret/calnex

Overlapping homologous superfamilies

Family relationships

  • Calreticulin/calnexin (IPR001580)


The calreticulin family is a family of calcium-binding ER chaperonesthat includes calreticulin, calnexin and camlegin [PMID: 12401114].

Calreticulin (calregulin) [PMID: 1497605] is a high-capacity calcium-binding protein which is present in most tissues and located at the periphery of the endoplasmic (ER) and the sarcoplamic reticulum (SR) membranes. It probably plays a role in the storage of calcium in the lumen of the ER and SR and it may well have other important functions.

Structurally, calreticulin is a protein of about 400 amino acid residues consisting of three domains:

  • An N-terminal, probably globular, domain of about 180 amino acid residues (N-domain).
  • A central domain of about 70 residues (P-domain) which contains three repeats of an acidic 17 amino acid motif. This region binds calcium with a low-capacity, but a high-affinity.
  • A C-terminal domain rich in acidic residues and in lysine (C-domain). This region binds calcium with a high-capacity but a low-affinity.

Calreticulin is evolutionarily related to several other calcium-binding proteins, including Onchocerca volvulus antigen RAL-1, calnexin [PMID: 8203019] and calmegin [PMID: 8126001].

GO terms

Biological Process

GO:0006457 protein folding

Molecular Function

GO:0005509 calcium ion binding
GO:0051082 unfolded protein binding

Cellular Component

GO:0005783 endoplasmic reticulum

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.