Abstract
Eye-derived growth factor I (EDGF-I), the retinal form of the basic fibroblast growth factor, has been purified to homogeneity from bovine retina by heparin-Sepharose chromatography. The radioiodinated EDGF-I retained full mitogenic activity and was used to study the interaction of the growth factor with bovine epithelial lens cells. We showed that 125I-labeled EDGF-I bound in a saturable and reversible manner to a specific cellular receptor. Scatchard analysis of the equilibrium binding gave a Kd of 53 X 10(-12) M with approximately equal to 20,000 binding sites per cell. Crosslinking experiments using two homobifunctional reagents induced the formation of a specific major complex with a Mr of approximately equal to 145,000, as determined by NaDodSO4/PAGE, and independent of reducing conditions. These data establish the existence of a receptor for the basic growth factor derived from neural tissues and give an estimation of the size of this receptor at Mr 130,000.