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Affinity labeling of a cell surface receptor for epidermal growth factor
Progress in Clinical and Biological Research
|January 1, 1978
Summary
Researchers identified the epidermal growth factor (EGF) receptor on 3T3 cells using a photoreactive EGF derivative. This method revealed a 190,000-dalton crosslinked complex, confirming EGF receptor binding and cell surface localization.
Area of Science:
- Biochemistry
- Cell Biology
- Molecular Biology
Background:
- The epidermal growth factor (EGF) plays a crucial role in cell growth and differentiation.
- Identifying and characterizing the EGF receptor is essential for understanding cellular signaling pathways.
Purpose of the Study:
- To identify and characterize the membrane receptor for epidermal growth factor (EGF) on 3T3 cells.
- To investigate the binding and localization of the EGF receptor using a novel labeling technique.
Main Methods:
- Utilized a photoreactive derivative of 125I-labeled EGF for specific radiochemical labeling.
- Employed sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS-PAGE) to analyze crosslinked complexes.
- Investigated cell surface accessibility using trypsin digestion at different temperatures.
Main Results:
- A major radioactive band at approximately 190,000 daltons was observed, corresponding to the EGF-receptor complex.
- The formation of this complex was directly proportional to EGF binding activity and absent in non-binding variants.
- The crosslinked complex was located on the cell surface and was susceptible to trypsin digestion at 4°C.
- At 37°C, the complex was processed into smaller forms (<58,000 daltons) resistant to trypsin.
Conclusions:
- Successfully identified and characterized the EGF receptor on 3T3 cells.
- Demonstrated the cell surface localization and binding characteristics of the EGF receptor.
- Provided insights into the post-binding processing of the EGF-receptor complex within the cell.