Characterization of the mouse placental epidermal growth factor receptor: changes in receptor number with day of gestation.

The epidermal growth factor (EGF) receptor is present in the mouse placenta in both a low- and a high-affinity form having approximate values for Ka of 10(7) M-1 and 10(9) M-1, respectively. No significant difference (P greater than or equal to 0.05) in the number of receptors existed between placental membrane preparations from days 10 and 17, both for the low- and the high-affinity receptor. The number of both high- and low-affinity receptors was significantly lower (P less than 0.05) for day 14 placental membranes than for either day 10 or day 17 placental membranes. Cross-linking of 125I-EGF to placental membranes resulted in the specific labelling of two major receptor forms with approximate molecular weights of 170,000 and 154,000, as determined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis.