V-Set Domain Containing T-Cell Activation Inhibitor 1 (VTCN1)

B7H4 belongs to the B7 family of costimulatory proteins. These proteins are expressed on the surface of antigen-presenting cells and interact with ligands on T lymphocytes.The predicted 282-amino acid protein, which is 87% identical to the mouse protein, contains a 2-amino acid intracellular domain, a large hydrophobic type I transmembrane region, and an extracellular domain with several N-glycosylation sites and conserved cysteine residues. Northern blot analysis revealed expression of a 1.8-kb transcript in spleen, lung, and thymus, and RT-PCR analysis detected expression in a wide range of tissues. Immunohistochemical and flow cytometric analyses showed expression on activated but not fresh T cells, B cells, monocytes, and dendritic cells.