Gi24, Recombinant, Human, Fc Chimera (B7-H5, C10orf54, Dies1, Gi24, ISP1, VISTA)

Platelet receptor Gi24, also known as Dies1, VISTA, SISP1 and B7-H5, is a 55�65kD transmembrane glycoprotein with homology to B7�like immune co�stimulatory molecules (1, 2). Mature human Gi24 contains a 162 amino acid (aa) extracellular domain (ECD) with one V�type Ig�like domain, a 21aa transmembrane segment, and a 96 aa cytoplasmic domain. Within the ECD, human Gi24 shares 70% and 67% aa sequence identity with mouse and rat Gi24, respectively (3). The 30kD ECD can be shed by MT1�MMP, with a 25�30kD fragment remaining in the membrane (3). Gi24 promotes both MT1�MMP expression and the MT1�MMP mediated activation of MMP�2 (3). Gi24 supports the differentiation of embryonic stem cells (ESC) and enhances BMP�4 induced signaling in ESC, but is also down�regulated following BMP�4 exposure (4, 5). It binds to BMP�4 directly, and also associates with the type I BMP receptor Activin RIB/ALK-4 (4, 5). Gi24 is expressed on the surface of na�ve CD4+ T cells and regulatory T cells (6). It is up�regulated in vivo on activated monocytes and dendritic cells (5). Gi24 inhibits CD4+ and CD8+ T cell proliferation, and their production of IL�2 and IFN-F (6). Its expression on tumor cells attenuates the anti�tumor immune response and enables more rapid tumor progression (6). In contrast, Gi24 limits disease progression in the autoimmune disease model EAE (6). Source: Recombinant protein corresponding to aa33-194 from human Gi24/VISTA/B7-H5 NS0-derived N-terminus (Accession# AAH20568). Moleclar weight ~44.8kD Endotoxin: <0.01EU/ug Biological Activity: Measured by its ability to inhibit anti-CD3 antibody induced IL-2 secretion in human T lymphocytes. The ED50 for this effect is typically 1-6ug/ml. Storage and Stability: Lyophilized powder may be stored at -20 degrees C. Stable for 12 months at -20 degrees C. Reconstitute with sterile buffer. Aliquot to avoid repeated freezing and thawing. Store at -20 degrees C. Reconstituted product is stable for 6 months at -20 degrees C. 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.