Pigment epithelium-derived factor (PEDF), a potent blocker of angiogene-sis in vivo, and of endothelial cell migration and tubule formation, binds with high affinity to an as yet unknown protein on the surfaces of endothe-lial cells. Given that protein fingerprinting suggested a match of a 60 kDa PEDF-binding protein in bovine retina withBos taurusF1-ATP synthase b-subunit, and that F1Fo-ATP synthase components have been identified recently as cell-surface receptors, we examined the direct binding of PEDF to F1. .
