Duplication of primate and rodent B7-H3 immunoglobulin V- and C-like domains: divergent history of functional redundancy and exon loss.
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Ling V, Wu PW, Spaulding V, Kieleczawa J, Luxenberg D, Carreno BM, Collins M
Duplication of primate and rodent B7-H3 immunoglobulin V- and C-like domains: divergent history of functional redundancy and exon loss.
Genomics. 2003 Sep;82(3):365-77. doi: 10.1016/s0888-7543(03)00126-5.
- PubMed ID
- 12906861 [ View in PubMed]
- Abstract
B7-H3 is a novel protein structurally related to the B7 family of ligands by the presence of a single set of immunoglobulin-V-like and immunoglobulin-C-like (VC) domains. By multiplex PCR, the dominantly expressed form of human B7-H3 was found to be a splice variant containing tandemly duplicated VC domains (VCVC). In contrast, mouse B7-H3 cDNA contained only one single VC form due to an exon structure corresponding to V-(pseudoexon C)-(pseudoexon V)-C. Comparisons of human, monkey, mouse, and hamster genomic B7-H3 reveal that primates, but not rodents, exhibited a higher degree of intramolecular sequence similarity between VC duplications than between molecules. Both VC and VCVC forms of human B7-H3 inhibited CD4(+) T cell proliferation and downregulated cytokine production upon TCR activation. These results suggest independent, but convergent, paths of B7-H3 active domain duplication followed by divergent histories of exon degeneration in rodents and exon maintenance by humans.