Exogenous ATP and other nucleoside phosphates modulate epidermal growth factor receptors of A-431 epidermoid carcinoma cells.

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Abstract
The binding of epidermal growth factor (EGF) by A-431 human epidermoid carcinoma cells was reduced after exposure of the cells to low concentrations (0.01-1 mM) of ATP and other nucleoside 5''-triphosphates at 37.degree. C, but not at 0.degree. C. This was due to loss of high-affinity EGF binding sites. The modulation was associated with transient increases in inositol phosphate synthesis and intracellular Ca2+ and with phosphorylation of the EGF receptor on serine and threonine. There was no evidence for entry of labeled ATP into the cells. ATP appeared to bind to specific cell surface receptors. Such binding was demonstrated directly with the nonmetabolizable ATP analogue adenosine 5''-[.beta.,.gamma.-imido]triphosphate.