CD97

CD97 (ADGRE5) is a leukocyte-enriched adhesion GPCR that undergoes GAIN-domain autoproteolysis into tethered N- and C-terminal fragments. Alternative splicing of its extracellular EGF modules generates isoforms with different ligand-binding properties; the longest isoform binds CD55 (decay-accelerating factor) on neighboring cells, while other regions engage chondroitin sulfate, linking CD97 to leukocyte migration, adhesion and activation at inflammatory sites. CD97 is expressed on granulocytes, monocytes and activated T cells, and is strongly upregulated in thyroid carcinoma, glioblastoma and other tumors, where it correlates with invasiveness. Blocking antibodies against CD97 are being explored for tumor targeting.