Chaperone Function of Calreticulin When Expressed in the Endoplasmic Reticulum as the Membrane-anchored and Soluble Forms

• DOI: 10.1074/jbc.270.35.20298
• Publication Date: 2002-07-26T14:57:46Z
• Authors: Ikuo Wada; Shin-ichi Imai; Masahiro Kai; Fumio Sakane; Hideo Kanoh
• Keywords: Calnexin; Chaperone (clinical)

A unique type of chaperone that requires glucose trimming the target proteins has been shown to be important for their maturation in endoplasmic reticulum (ER). Calnexin, an ER membrane chaperone, is first example such a class. Here, we focus on calreticulin, major luminal protein, which shares with calnexin two sets characteristic sequence repeat. We evaluated function calreticulin by expressing it surface. constructed membrane-anchored chimera fusing truncated membrane-anchoring tagged segment calnexin. When expressed HepG2 cells, transiently interacted set nascent secretory castanospermine-sensitive manner. The spectrum recognized was remarkably similar observed Next, tested if at its physiological location. Luminally preferentially bound transferrin and released upon chase. Association other ligands observed, however, low efficiencies. Interactions were abrogated castanospermine treatment. conclude per se another apparently same characteristics as selectively interacts lumen, suggesting may cover diversity maturations.