Galectin 9 is a β-galactoside-binding protein encoded by the LGALS9 gene and a member of the galectin family.1 It contains two non-identical carbohydrate recognition domains (CRDs) joined by a peptide linker, the length of which depends on alternative splicing of the LGALS9 gene, which produces a short, medium, or long variant of the protein.1,2 The non-identical CRDs are responsible for binding to different types of saccharide ligands with the N-terminal CRD (NCRD) preferring more complex glycoconjugates.1 Galectin 9 is localized to the cytosol, nucleus, and extracellular matrix and is expressed primarily in immune-related tissues and cells.3 When expressed on immune or tumor cells, galectin 9 binds to glycosylated sites on the immunoregulatory protein TIM-3 and activates signaling that impairs immune synapse formation leading to T cell anergy or apoptosis.4 It also binds to the transmembrane glycoprotein CD44 on osteoblasts, leading to their proliferation, and it has a role in cell adhesion by preventing hyaluronic acid from binding to CD44.5 The short variant of galectin 9 acts as an eosinophil chemoattractant.6 It also activates CD4+ T cell populations and induces naïve T cells to acquire a central memory T cell (TCM) phenotype.7 Galectin 9 was originally identified as a tumor antigen in patients with Hodgkin’s disease.1 It is expressed to a lower extent in tumor cells compared with non-tumor cells but is increased in leukemia and colon cancer cell lines.3 Increased expression of the short variant of galectin 9 inhibits or enhances adhesion in breast or colon cancer cell lines, respectively. The expression of the short variant of galectin 9 is increased by interferon γ (IFN-γ) in synovial fibroblasts isolated from patients with rheumatoid arthritis.8 Cayman's Galectin 9 Short Variant (human, recombinant) protein is a disulfide-linked homodimer. The reduced monomer, comprised of galectin 9 (amino acids 2-323) fused to human IgG1 Fc at its N-terminus, consists of 554 amino acids and has a calculated molecular weight of 61.8 kDa.WARNING This product is not for human or veterinary use.
