Figure 1.

Structure and Expression of B7-H3 (CD276). B7-H3 is encoded by the exons located on chromosome 9 in mice and on chromosome 15 in humans. The molecule consists of a short cytoplasmic tail, a single transmembrane sequence, and extracellular immunoglobulin domains. In mice, the extracellular domain is composed of an N-terminal IgV and a C-terminal IgC, while in humans, the predominant isoform is 4IgB7-H3, which contains two duplicated IgV-IgC domains. B7-H3 expression varies among different brain tumors but is rarely expressed on normal cells. In addition to the membrane-bound form, the soluble form of B7-H3 has also been detected in human plasma.