Member database | PROSITE patterns |
PROSITE patterns type | conserved site |
Short name | CALRETICULIN_REPEAT |
Description
Calreticulin
[2] (also known as calregulin, CRP55 or HACBP) 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:
a) An N-terminal, probably globular, domain of about 180 amino acid residues
(N-domain);
b) 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;
c) 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 evolutionary related to the following proteins:
- Onchocerca volvulus antigen RAL-1. RAL-1 is highly similar to calreticulin,
but possesses a C-terminal domain rich in lysine and arginine and lacks
acidic residues and is therefore not expected to bind calcium in that
region.
- Calnexin
[3]. A calcium-binding protein that interacts with newly
synthesized glycoproteins in the endoplasmic reticulum. It seems to play a
major role in the quality control apparatus of the ER by the retention of
incorrectly folded proteins.
- Calmegin
[1] (or calnexin-T), a testis-specific calcium-binding protein
highly similar to calnexin.
We developed three signature patterns for this family of proteins. The first
two patterns are based on conserved regions in the N-domain; the third pattern
corresponds to positions 4 to 16 of the repeated motif in the P-domain.
References
1.Molecular cloning of a novel Ca(2+)-binding protein (calmegin) specifically expressed during male meiotic germ cell development. Watanabe D, Yamada K, Nishina Y, Tajima Y, Koshimizu U, Nagata A, Nishimune Y. J. Biol. Chem. 269, 7744-9, (1994). View articlePMID: 8126001
2.Calreticulin. Michalak M, Milner RE, Burns K, Opas M. Biochem. J. 285 ( Pt 3), 681-92, (1992). View articlePMID: 1497605
3.Calnexin: a membrane-bound chaperone of the endoplasmic reticulum. Bergeron JJ, Brenner MB, Thomas DY, Williams DB. Trends Biochem. Sci. 19, 124-8, (1994). View articlePMID: 8203019