Galectins comprise a family of multi- functional carbohydrate-binding proteins with specificity for N-acetyl-lactosamine-containing glycoproteins. At least 14 mammalian Galectins share structural similarities in their carbohydrate recognition domains (CRD), forming three groups. Full length Galectin-9 is a widely expressed 39kD tandem-repeat Galectin that contains two CRDs connected by a linker region. Progressive deletion within the linker region generates a 36kD isoform and a 35kD isoform. This recombinant protein corresponds to the Ecalectin isoform of human Galectin-9 and shares 70% and 73% aa sequence identity with mouse and rat Galectin-9, respectively. Galectin-9 exhibits a wide range of activities. All three isoforms function as eosinophil chemoattractants. This activity is destroyed by thrombin-mediated cleavage within the linker region of the long isoform, although the Ecalectin isoform is resistant to thrombin. Galectin-9 binds to carbohydrate moieties of IgE, thereby preventing immune complex formation, mast cell degranulation, and asthmatic and cutaneous anaphylaxis reactions. Independent of its lectin properties, Galectin-9 induces the maturation of dendritic cells which promote Th1 polarization. Galectin9 induces cellular apoptosis in part by direct binding to TIM-3. Its interaction with TIM-3 inhibits Th1 cell and CD8+ cytotoxic T cell responses and also promotes regulatory T cell differentiation and activity. Galectin-9 suppresses tumor cell metastasis by interfering with the associations between hyaluronic acid and CD44 and between VCAM-1 and Integrin a4b1. The Ecalectin isoform can also be expressed as an integral membrane protein and mediate the cellular efflux of urate. Recombinant protein corresponding to Ala2-Thr323 from human Galectin-9 expressed in E. coli. Accession: BAA31542. Activity: 1. Measured by its ability to induce apoptosis of Jurkat human acute T cell leukemia cells. The ED50 for this effect is typically 1-5ug/ml. 2. Measured by its binding ability in a functional ELISA. Storage and Stability: Lyophilized and reconstituted products are stable for 6 months after receipt at -20C. Reconstitute with sterile ddH2O. Aliquot to avoid repeated freezing and thawing. Store at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.
