Calnexin: Proteins and Enzymes

Calnexin, an abundant approx. 90kDa integral protein of the endoplasmic reticulum, is also referred to as IP90, p88 and p90 (1). It consists of a large 50kDa N-terminal calcium-binding luminal domain, a single transmembrane helix and a short acidic cytoplasmic tail (2, 3). Unlike its ER counterparts which have a KDEL sequence on their Cterminus to ensure ER retention (4), calnexin has positively charged cytosolic residues that do the same thing (3). Most ER proteins act as molecular chaperones ...