Antigen Description
B7-1 and B7-2, together with their receptors CD28 and CTLA4, constitute one of the dominant costimulatory pathways that regulate T and B cell responses. Although both CTLA4 and CD28 can bind to the same ligands, CTLA4 binds to B7-1 and B7-2 with a 20-100 fold higher affinity than CD28 and is involved in the down-regulation of the immune response. B7-1 is expressed on activated B cells, activated T cells, and macrophages. B72 is constitutively expressed on interdigitating dendritic cells, Langerhans cells, peripheral blood dendritic cells, memory B cells, and germinal center B cells. Additionally, B7-2 is expressed at low levels on monocytes and can be upregulated through interferon gamma. B7-1 and B7-2 are both members of the immunoglobulin superfamily. Human B7-2 is a 329 amino acid (aa) protein containing a putative 329 amino acid (aa) protein containing a putative 23 aa signal peptide, a 224 aa extracellular domain, a 21 aa transmembrane domain, and a 61 aa cytoplasmic domain. Human B7-2 and B7-1 share 26% amino acid identity. Human and mouse B7-2 share 50% amino acid identity. However, it has been observed that both human and mouse B7-1 and B7-2 can bind to either human or mouse CD28 and CTLA4, suggesting that there are conserved amino acids which form the B7-1/B7-2/CD28/CTLA4 critical binding sites.
COA
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