Ligand-mediated autophosphorylation activity of the epidermal growth factor receptor during internalization

Journal Article · Fri Dec 01 00:00:00 EST 1989 · Journal of Cell Biology; (USA)

DOI:https://doi.org/10.1083/jcb.109.6.2751· OSTI ID:5037659

Lai, W H; Cameron, P H; Doherty, II, J J; Posner, B I; Bergeron, J J ^[1]

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1. McGill Univ., Montreal, Quebec (Canada)

The association of EGF with its receptor in endosomes isolated from rat liver homogenates was assessed biochemically by polyethylene glycol precipitation and morphologically by electron microscope radioautography. The proportion of receptor-bound ligand in endosomes at 15 min after the injection of doses of 0.1 and 1 microgram EGF/100 g body weight was 57%. This value increased to 77% for the dose of 10 micrograms EGF injected. Quantitative electron microscope radioautography carried out on endosomes isolated at 15 min after the injection of 10 micrograms 125I-EGF demonstrated that most radiolabel was over the endosomal periphery thereby indicating that ligand-receptor complexes were in the bounding membrane but not in intraluminal vesicles of the content. EGF receptor autophosphorylation activity during internalization was evaluated in plasmalemma and endosome fractions. This activity was markedly but transiently reduced on the cell surface shortly after the administration of saturating doses of EGF. The same activity, however, was augmented and prolonged in endosomes for up to 30 min after EGF injection. The transient desensitization of cell surface activity was not due to prior in vivo phosphorylation since receptor dephosphorylation in vitro failed to restore autophosphorylation activity. Transient desensitization of cell surface autophosphorylation activity coincided with a diminished capacity for endocytosis of 125I-EGF with endocytosis returning to normal after the restoration of cell surface autophosphorylation activity. The inhibition of cell surface autophosphorylation activity and the activation of endosomal autophosphorylation activity coincident with downregulation suggest that EGF receptor traffic is governed by ligand-regulated phosphorylation activity.

• OSTI ID: 5037659
• Journal Information: Journal of Cell Biology; (USA), Vol. 109; ISSN 0021-9525
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
GROWTH FACTORS
RECEPTORS
PHOSPHORYLATION
AUTORADIOGRAPHY
BIOCHEMICAL REACTION KINETICS
CELL MEMBRANES
EPIDERMIS
IODINE 125
LIGANDS
LIVER
PHAGOCYTOSIS
RATS
ANIMAL TISSUES
ANIMALS
BETA DECAY RADIOISOTOPES
BODY
CELL CONSTITUENTS
CHEMICAL REACTIONS
DAYS LIVING RADIOISOTOPES
DIGESTIVE SYSTEM
ELECTRON CAPTURE RADIOISOTOPES
EPITHELIUM
GLANDS
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPES
KINETICS
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
MITOGENS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PROTEINS
RADIOISOTOPES
REACTION KINETICS
RODENTS
SKIN
TISSUES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques