Epidermal growth factor-like transforming growth factor. II. Interaction with epidermal growth factor receptors in human placenta membranes and A431 cells.

摘要: A 125I-labeled derivative of rat epidermal growth factor-like transforming factor (125I-eTGF) that retains the chemical and biological properties native eTGF has been prepared to characterize interaction with (EGF) membrane receptors. Binding 125I-eTGF mouse EGF (125I-EGF) preparations from human placenta A431 epidermoid carcinoma cell line was competed for same extent potency by either unlabeled or EGF. Components membranes (145-170 kDa) were major species affinity-labeled cross-linking membrane-bound 125I-EGF. Affinity labeling these receptor fully inhibited both when present in excess during incubation The binding affinity capacity receptors strikingly similar However, highly sensitive pH, being optimal only within pH 8.0-8.5 range whereas at 7.0-9.0. modified parallel exposure placental phytohemagglutinin, concanavalin A, wheat germ agglutinin. Prolonged cells induced down-regulation binding. eTGF-induced followed kinetics as EGF-induced down-regulation. data indicate despite limited sequence homology between EGF, two ligands exhibit a remarkably mode common eTGF/EGF type.