Association of the epidermal growth factor receptor kinase with the detergent-insoluble cytoskeleton of A431 cells.

Abstract

The epidermal growth factor receptor (EGF-R) on human epidermoid carcinoma cells, A431, was found to be predominantly associated with the detergent-insoluble cytoskeleton, where it retained both a functional ligand-binding domain and an intrinsic tyrosine kinase activity. The EGF-R was constitutively associated with the A431 cytoskeleton; this association was not a consequence of adventitious binding. The EGF-R was associated with cytoskeletal elements both at the cell surface, within intracellular vesicles mediating the internalization of the hormone-receptor complex, and within lysosomes. The EGF-R became more stably associated with cytoskeletal elements after its internalization. The cytoskeletal association of the EGF-R was partially disrupted on suspension of adherent cells, indicating that alteration of cellular morphology influences the structural association of the EGF-R, and that the EGF-R is not intrinsically insoluble.Cytoskeletons prepared from EGF-treated A431 cells, when incubated with ,1,-32p-ATP, demonstrated enhanced autophosphorylation of the EGF-R in situ as well as the phosphorylation of several high molecular weight proteins. In this system, phosphorylation occurs between immobilized kinase and substrate. The EGF-R and several high molecular weight cytoskeletal proteins were phosphorylated on tyrosine residues; two of the latter proteins were phosphorylated transiently as a consequence of EGF action, suggesting that EGF caused the active redistribution of the protein substrates relative to protein kinases. The ability of EGF to stimulate protein phosphorylation in situ required treatment of intact cells at physiological temperatures; addition of EGF directly to cytoskeletons had no effect. These data suggest that the structural association of the EGF-R may play a role in cellular processing of the hormone, as well as in regulation of the EGF-R kinase activity and in specifying its cellular substrates.

Extracellular matrix modulates epidermal growth factor receptor activation in rat glomerular epithelial cells.

“…Thus, the amount of EGF-R internalization appeared to be determined primarily by signals from ECM, perhaps via the cytoskeleton. This view is supported by the recent demonstration that EGF-R is an actin-binding protein (31) and that EGF-R trafficking may be associated with receptor-cytoskeleton interactions (32,33). By analogy to EGF-R metabolism in the liver (9), the increased rate of EGF-R internalization in GEC on plastic may have rendered the receptor more accessible to an EGF-R-directed endosomal PTPase, with consequent dephosphorylation.…”

Auxins and Cytokinins as Antipodal Modulators of Elasticity within the Actin Network of Plant Cells

“…profilin, myosin, and microtubule-associated proteins, and differences in the degree of interaction with the plasma membrane components, e.g. polyphosphoinositides, transmembrane proteins, and G proteins (Edelman, 1976;Schliwa et al, 1984;Landreth et al, 1985;Adams and Pollard, 1989;Goldschmidt-Clermont et al, 1990;Luna and Hitt, 1992;Ridley and Hall, 1992;Shariff and Luna, 1992;Williamson, 1993).…”

Flow cytometric detection of the association between cell surface receptors and the cytoskeleton

“…To realize the biochemical reactions in signal transduction, a local assembly of molecules to react with each other appears to be necessary (3,4,17). The cytoskeleton can serve as an intracellular structure to which receptors, cytoskeletal proteins, and other signaling molecules can be immobilized in close proximity to enable local biochemical reactions (2,10,11,23,26). Furthermore, the fact that cell surface receptors can physically link to the cytoskeleton implies the possibility that mechanical forces can be transduced by receptors through the cell membrane directly to the cytoskeleton, which could give rise to biochemical events (8,24,25).…”