C1GALT1C1. also known as COSMC, is a crucial chaperone protein required for the proper folding and activity of C1GALT1 (core 1 β1.3-galactosyltransferase). This enzyme is essential for synthesizing core 1 O-glycans, a common structural motif in mucin-type O-glycosylation. O-glycosylation plays vital roles in protein stability, cell adhesion, and immune responses. Dysregulation of C1GALT1C1 disrupts normal O-glycan patterns, leading to truncated structures like the Tn antigen (GalNAcα1-O-Ser/Thr), which is associated with cancer progression, autoimmune disorders, and rare genetic conditions such as Tn syndrome.
Antibodies targeting C1GALT1C1 are valuable tools for studying glycosylation defects in diseases. In cancer research, these antibodies help detect COSMC mutations or epigenetic silencing, which correlate with metastatic potential and poor prognosis in carcinomas. They are also used to explore autoimmune mechanisms, as abnormal O-glycans may trigger autoantibodies in conditions like IgA nephropathy. Commercially available C1GALT1C1 antibodies (e.g., monoclonal or polyclonal) are optimized for techniques like Western blotting, immunohistochemistry, and flow cytometry. However, specificity validation remains critical due to homology with other chaperones. Recent studies further investigate C1GALT1C1's role in immune evasion, highlighting its potential as a therapeutic target or biomarker for glycoengineering-based therapies.