To be or not to be B7
J. Clin. Invest. Xingxing Zang, et al. 116:2590 doi:10.1172/JCI30103 [Go to this article.]

Figure 1
Phylogeny of VSIG4 and hypothetical models of its role as a T cell inhibitor. (A) VSIG4, A33, and junctional adhesion molecule A (JAM-A) are grouped together in a phylogenetic tree, whereas representatives of the B7 family (B7-1, CD274, and V-set domain–containing T cell activation inhibitor 1 [VTCN1]) and CR1 and CR2 are divergent. All the sequence alignments and homology comparisons were performed with MacVector 7.0. (Accelrys). The phylogenetic tree was generated by Phylogenetic Analysis Using Parsimony (PAUP 4.0b10; Sinauer Associates Inc.) with sequence alignment by removal of significant inserts and trimming C- and N-terminal extensions. (B) T cells express an unidentified receptor for VSIG4 expressed on macrophages. The ligation of this receptor downregulates TCR-mediated signaling to the nucleus. Alternatively, VSIG4 on macrophages and CR1/CR3 on T cells bind the same multimeric C3b or iC3b molecules, which in turn triggers a signal resulting in inhibition of T cell activation.