CHARACTERIZATION AND AUTORADIOGRAPHIC LOCALIZATION OF THE EPIDERMAL GROWTH-FACTOR RECEPTOR IN THE JEJUNUM OF NEONATAL AND WEANED PIGS

Receptors for epidermal growth factor (EGF) were characterized on the intestinal membranes of newborn, sucking and weaned pigs. I-125-labelled EGF (I-125-EGF) binding to membrane homogenates was time-dependent, saturable, linearly correlated to membrane protein and reversible. Analysis of saturation curve data revealed a single class of I-125-EGF binding sites in both newborn and weaned pigs. Receptor levels tended to be higher in weaned than in newborn pigs; the converse was true for the receptor affinity. In contrast, virtually no binding sites were found on the intestinal membranes of sucking pigs. Autoradiography in vitro of jejunal sections of newborn and weaned pigs demonstrated I-125-EGF receptors on both microvillar and basolateral surfaces of enterocytes, suggesting that luminal EGF could influence developmental processes in the intestine either directly or indirectly following transcytosis of the ligand.