BIOCHEMICAL-CHARACTERIZATION OF EPIDERMAL GROWTH-FACTOR RECEPTOR IN SYRIAN-HAMSTER BUCCAL POUCH

Binding of [I-125]-epidermal growth factor (EGF) to the membrane of th e adult hamster buccal pouch was specific and protein concentration de pendent, and was significantly higher than that of rat buccal tissue ( hamster versus rat; 12.1 +/- 0.9 versus 9.77 +/- 0.22 fmol/mg protein, mean +/- SD, n = 5, p < 0.01). The higher binding was due to a higher receptor number (B-max). Western blot analysis using anti-EGF recepto r antibody revealed four immunoreactive protein bands of 170, 150, 116 and 55 kDa in hamster buccal membrane preparations. In a separate exp eriment, the EGF concentration in the phosphate-buffered saline extrac t of the hamster submandibular gland was determined by radioimmunoassa y; the lever was significantly much lower (p < 0.01) than that of rat or mouse (hamster, rat, mouse; 24.2 +/- 2.6, 123 +/- 17, 5950 +/- 171 ng/g wet tissue; mean +/- SD, n = 3). The findings suggest that hamste r buccal pouch is particularly well suited to the study of the biologi cal functions of oral EGF receptor.