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Updated: Jun 17, 2026

Targeting Cysteine Thiols for in Vitro Site-specific Glycosylation of Recombinant Proteins
Published on: October 4, 2017
Cyclophilin C-associated protein/Mac-2 binding protein colocalizes with calnexin and regulates the expression of
Wuyi Kong1, Bryan W Lin, Shaowei Li
1Children's Surgical Research Program, Stanford University School of Medicine, Stanford, California 94305-5148, USA. wkong@stanford.edu
Abstract:
Cyclophilin C-associated protein (CyCAP) or Mac-2 binding protein has been identified as a binding protein for cyclophilin C in mice and for Mac-2 (galectin-3) in human, suggesting its multiple binding activity to proteins. In the present study, using specific anti-rat-CyCAP antibody, we found that CyCAP colocalizes with calnexin at the location near the nuclear envelope, however CyCAP does not have colocalization with calreticulin. In senescent fibroblasts and interferon-gamma (IFNgamma) treated fibroblasts, both calnexin and CyCAP form larger polymers and are released from the endoplasmic reticulum (ER) through the cellular membrane to the extracellular area. Immunoprecipitation studies further confirm that the release of calnexin is through binding to CyCAP. Further, we found that tissue transglutaminase (tTG) protein is decreased, however not at the RNA level, in CyCAP null fibroblasts, which suggests that CyCAP is involved in tTG post-translational modification. Our data give novel evidence that CyCAP regulates the post-translational modification of tTG through its colocalization with calnexin in ER.
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