Recombinant Human ICOS Fc Chimera Avi-tag Protein, CF

Inducible co-stimulator (ICOS), also called AILIM (activiation-inducible lymphocyte immunomediatory molecule) and CRP-1 (CD28-related protein-1), is a member of the growing CD28 family of immune co-stimulatory receptors. Other family members are CD28, CTLA-4 and PD-1. Human ICOS is a homodimeric type I transmembrane protein consisting of 199 amino acids (aa) with a putative 20 aa signal sequence, a 121 aa extracellular domain, a 23 aa transmembrane region, and a 35 aa cytoplasmic domain. ICOS shares approximately 39% amino acid similarity with CD28 and CTLA-4. Human and mouse ICOS share approximately 72% amino acid identity. ICOS is expressed on most CD45RO+ cells. ICOS expression is up-regulated within approximately 24-48 hours of activation on Th primed cells. B7-H2, a member of the B7 family of co-stimulatory ligands, has been identified as the ICOS ligand. The B7-H2/ICOS interaction appears to play roles in T cell dependent B cell activation and Th differentiation. Our Avi-tag Biotinylated ICOS Fc Chimera features biotinylation at a single site contained within the Avi-tag, a unique 15 amino acid peptide. Protein orientation will be uniform when bound to streptavidin-coated surface due to the precise control of biotinylation and the rest of the protein in unchanged so there is no interference in the protein's bioactivity.