Membrane components that interact with
epidermal growth factor (
EGF) and
transforming growth factors (TGFs) have been identified by covalent crosslinking to their respective 125I-labeled
ligands. Under appropriate conditions,
disuccinimidyl suberate or
hydroxysuccinimidyl p-azidobenzoate cross-link receptor-bound 125I-labeled
EGF to a 140- to 170-kilodalton (kDal) receptor species in membranes from both A431 human
carcinoma cells and normal rat kidney cells. 125I-Labeled
sarcoma growth factor (SGF), a TGF from virally transformed mouse 3T3 cells, also can be affinity-crosslinked to the 140- to 170-kDal
EGF receptor species in membranes from A431 and rat kidney cells. The labeling of this receptor is inhibited when either excess unlabeled
EGF or SGF is present during incubation of membranes with either 125I-labeled
EGF or 125I-labeled SGF. In contrast, a second receptor species of 60 kDal is affinity-labeled with 125I-labeled SGF but not with 125I-labeled
EGF in membranes from both A431 and rat kidney cells. SGF and a TGF from virally transformed rat embryo cells inhibit the labeling of the 60-kDal species when present in excess during incubation of membranes with 125I-labeled SGF, whereas
EGF is completely ineffective in inhibiting the labeling of this receptor. The data suggest that a specific 60-kDal receptor that displays high affinity for TGFs but not for
EGF may mediate induction of the transformed phenotype. In addition, SGF and other TGFs interact with the 140- to 170-kDal
EGF receptor that appears to mediate normal cell growth effects.