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Subcellular localization of the EGF receptor maturation process.
S Gamou1, M Shimagaki, S Minoshima
1Department of Molecular Biology, Keio University School of Medicine, Tokyo, Japan.
Experimental Cell Research
|July 1, 1989
Summary
Epidermal growth factor (EGF) receptor acquires ligand binding activity late in its maturation, likely within the Golgi complex. This process is crucial for EGF receptor function and cellular signaling.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Glycosylation and processing of the epidermal growth factor (EGF) receptor are critical for its ligand binding activity.
- The precise cellular location where the EGF receptor gains EGF binding capability remains unclear.
Purpose of the Study:
- To investigate whether the EGF receptor acquires EGF binding activity in the endoplasmic reticulum (ER) or Golgi complex.
- To elucidate the kinetics of EGF receptor maturation and transport.
Main Methods:
- Utilized a hyperproducing cell line (NA) for EGF receptor studies.
- Performed parallel kinetic analysis of EGF binding activity and intracellular receptor transport.
- Employed immunoprecipitation with anti-EGF receptor antibody B4G7.
- Conducted pulse-chase experiments and subcellular fractionation.
Main Results:
- EGF binding-capable receptors appeared 30-60 minutes after [35S]methionine labeling.
- Pulse-chase experiments showed EGF binding activity emerged after a 30-minute pulse and 30-minute chase.
- Newly synthesized receptors were localized to the Golgi complex within 30 minutes.
- Receptors reached the Golgi complex and plasma membrane after a 30-minute chase, with only half exhibiting EGF binding.
Conclusions:
- EGF receptor transport from ER to Golgi occurs within 30 minutes, but binding activity is not yet acquired.
- Ligand binding activity is gained at a late maturation stage, predominantly in the Golgi complex.
- This finding clarifies a key step in EGF receptor functionalization.