Regulation of epidermal growth factor receptor number and phosphorylation by fasting in rat liver.

摘要: The binding of 125I-epidermal growth factor (EGF) to microsomal membrane preparations from the livers rats fasted for 72 h or fed control high carbohydrate diets was examined determine whether alterations in nutrient intake could affect EGF receptor system. Fasted had 40-50% less than did carbohydrate-fed rats. Scatchard analysis data indicated that decrease due a number with no change affinity. Cross-linking 125I-EGF receptors disuccinimidyl suberate revealed specific Mr 170,000 protein, which diminished by approximately 75% fasting, and = 150,000 accounted total labeling relatively unchanged fasting. sum 2 bands reduced 40% fasting is consistent reduction detected analysis. stimulated 1.5-3-fold increase 32P incorporation into one major protein 170 kDa all 3 groups. Basal EGF-stimulated autophosphorylation kDa, when normalized lower membranes animals, compared those comparable to, into, 170-kDa suggested kinase activity/receptor unaffected Moreover, activity groups an exogenous substrate, as judged equal basal phosphorylation Val5-angiotensin II, EGF-binding capacity. These results suggest regulates primarily regulation hepatic receptors. possibility exists some vivo effects may be mediated levels.