Effect of Triton X-100 on Insulin and Epidermal Growth Factor Receptor Binding and Autophosphorylation in Golgi Fractions and Partially Purified Receptors from Rat Liver

Epidermal growth factor (EGF) is a 6,000 Da polypeptide hormone produced by glands of the gastrointestinal tract, namely the salivary and Brunner's glands. It is found in a wide variety of external secretions as well as in blood and amniotic fluid. In fetal and neonatal life, EGF appears to play an important role in the development of the oral cavity, lungs, gastrointestinal tract and eyelids. Its presence in cells of the central nervous system suggests that it also plays a role in modulating the development of this system. In adult animals, the function of EGF is much less well understood. In rodents, it apparently modulates acid secretion from parietal cells in the stomach, and it undoubtedly plays an important role in wound healing, either through its localization within skin or by the licking of wounds with EGF-containing saliva. Considerable evidence now suggests that it may be one of the key factors in initiating liver regeneration after partial hepatectomy or chemical injury. The liver appears to be the principal organ which regulates the circulating level of EGF. In fact, EGF is cleared so efficiently by the liver that only the peripheral cells of the lobule (zone 1) sequester EGF, and little remains in the circulation for cells in the more distal zones (zones 2 and 3). In the liver, EGF normally binds to a plasma membrane receptor and is internalized within the liver cell, where the vast majority of EGF and its receptor are destroyed in lysosomes. A small but consistent quantity of EGF enters the bile intact. In the regenerating liver, however, the lysosomal pathway appears to be shut down, and the EGF is diverted to hepatocyte nuclei prior to the initiation of DNA synthesis. Nuclear EGF is found free as well as bound to a high-molecular-weight protein which has many characteristics identical to the plasma membrane EGF receptor. The plasma membrane receptor is a large transmembrane glycoprotein of 170,000 Da containing four domains: an extracellular EGF-binding portion, a hydrophobic membrane-spanning segment, a proximal cytoplasmic domain which binds ATP and protein substrates containing tyrosine for phosphorylation and a terminal cytoplasmic portion with 3 tyrosines which undergo autophosphorylation after EGF binding.(ABSTRACT TRUNCATED AT 400 WORDS)

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“…Both activities are primarily associated with plasma membrane fractions. EGF receptors are also found in microsomal and Golgi fractions (66).…”

Section: Egf Receptormentioning

confidence: 99%

Biological effects of epidermal growth factor, with emphasis on the gastrointestinal tract and liver: An update

1989

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“…For example, it was proposed that Triton X-100 intercalates into sarcoplasmic reticulum vesicles and interacts at low concentrations with the Ca2"1" ATPase to produce a functionally modified enzyme with low affinity for Ca2+ and no cooperativity between calcium ion binding sites (McIntosh & Davidson, 1984). Triton X-100 also affects ligand binding and autophosphorylation of insulin and epidermal growth factor receptors (Hwang et al, 1985). The conformational state of the mitochondrial adenine nucleotide carrier is dependent on the detergent used for its solubilization (Block & Vignais, 1986).…”

Section: Discussionmentioning

confidence: 99%

Nonionic detergents increase the stoichiometry of ligand binding to the rat hepatic galactosyl receptor

Ray¹,

Oka²,

Weigel³

1986

Biochemistry

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Expression of epidermal growth factor receptors in human lung tumors

Hwang

Tay

Lin

et al. 1986

Cancer

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Using the adjacent histologically normal tissues obtained from the same patients as controls, six human lung tumors were studied for the activities of epidermal growth factor (EGF) receptor binding, and receptor autophosphorylation. There was a 1.2- to 2.8-fold increase in EGF receptor activities in lung tumors due to an increase in the number of receptors without changes in their affinity. The increase had no direct correlation with the degree of differentiation or the type of lung tumors. The elevated expression of EGF receptor may be one of the characteristics in lung tumors. Epidermal growth factor and its receptor also may play a role in the regulatory mechanisms during tumorigenesis.

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Effect of Triton X-100 on Insulin and Epidermal Growth Factor Receptor Binding and Autophosphorylation in Golgi Fractions and Partially Purified Receptors from Rat Liver

Cited by 16 publications

References 21 publications

Biological effects of epidermal growth factor, with emphasis on the gastrointestinal tract and liver: An update

Biological effects of epidermal growth factor, with emphasis on the gastrointestinal tract and liver: An update

Nonionic detergents increase the stoichiometry of ligand binding to the rat hepatic galactosyl receptor

Expression of epidermal growth factor receptors in human lung tumors

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