Calnexin (CANX or p95 calnexin) binds Interleukin-27 subunit beta (EBI3, IL27B). In human cell lines (BL30, BL41, Louckes, BJAB, P3HR1) most newly synthesized EBI3 is retained in the endoplasmic reticulum (ER) in an endoglycosidase H-sensitive form (Devergne et al. 1996, 1997), bound to CANX and a 60-kDa protein and transiently with a p75-kDa protein, both ignored here). EBI3 can be released by itself but the association with CANX prevents this, the complex is retained in the ER. The co-expression of other interleukin subunits enables the release of EBI3 in a complex with Interleukin-27 subunit alpha (IL27) (Devergne et al. 1996).