ERp57




The thiol-disulfide oxidoreductase ERp57 is
 a soluble protein of the endoplasmic reticulum
 and the closest known homologue of protein disulfide isomerase.
 The protein interacts with the two lectin chaperones calnexin and
calreticulin and thereby promotes the oxidative folding of newly
synthesized glycoproteins.

Calreticulin

 

 alreticulin : calregulin, CRP55, CaBP3, calsequestrin-like protein,
and endoplasmic reticulum resident protein 60 (ERp60)
: a multifunctional protein that in humans is encoded by CALR gene.
it  binds Ca ion,  rendering it inactive. the Ca²⁺ is bound with low affinity but high capacity,
and can be released on a signal. Calreticulin is located in storage compartments associated
with the ER.

Calnexin

 

 Calnexin (CNX) is a 67 KDa integral protein.

is a chaperon, characterized by assisting protein folding

 and quality control, ensuring that only properly folded and 

assembled proteins proceed further along the secretory pathway.

Calnexin acts to retain unfolded or unassembled N-linked glycoprotein in the ER.