Insulin and Epidermal Growth Factor HUMAN FIBROBLAST RECEPTORS RELATED TO DEOXYRIBONUCLEIC ACID SYNTHESIS AND AMINO ACID UPTAKE

摘要: Receptors for insulin and epidermal growth factor (EGF) have been studied in confluent cultured intact human fibroblast monolayers. 125-I-EGF binds specifically to Half-maximal binding is observed at 4 times 10 minus M EGF; saturation of approximately 10-4 molecules EGF are bound per cell. 125-I-Insulin also by monolayers with half-maximal 9 insulin; about 10-3 cell saturation. Both stimulate thymidine incorporation alpha-aminoisobutyrate uptake. A effect M, both the stimulation uptake; EGF, uptake EGF. causes an apparent greater than does insulin, whereas same The degree either or varied (1.2- 2-fold) from one batch cells another, as did measured values K-m (average value 1 mM, range 0.6 2 mM) V-max (average, 0.82, 0.78 0.87 nmol/100 mug protein min) alpha-aminoisobutyrate. Nonetheless, each peptide was independent increase uptake, constant another. peptide-mediated can be attributed a decrease (e.g. insulin) 0.70 0.57 mM; 0.66 concomitant 0.80 0.84 nmol/min/100 protein). requires 40- 60-min period preincubation blocked pretreating cycloheximide. In presence ouabain, peptides inhibit rather ouabain lowers basal rate 3-0-methyl-D-glucose not affected under conditions where stimulates fat transport. These observations indicate that fibroblasts possess specific sites which related two actions peptides: