Nov 25, 1989

The 75,000-dalton interleukin-2 receptor transmits a signal for the activation of a tyrosine protein kinase

The Journal of Biological Chemistry
E M SaltzmanJ E Casnellie

Abstract

The high-affinity receptor for interleukin-2 (IL-2) is composed of two distinct subunits with molecular weights of 55,000 and 75,000 (p55 and p75). While the presence of the high-affinity receptor requires the simultaneous expression of p55 and p75, these subunits can also be expressed independently, resulting in IL-2 receptors with low and intermediate affinities, respectively. IL-2 can induce proliferation in cells expressing either the intermediate affinity p75 receptor or the p55.p75 high-affinity complex, suggesting that p75 is responsible for signal transduction. We have previously shown that signal transduction by the high-affinity IL-2 receptor involves the activation of a tyrosine protein kinase. In order to evaluate the role of p75 in the activation of this kinase we assessed the ability of IL-2 to induce the activation of a tyrosine protein kinase in the human leukemic cell lines Hut 78 and YT. These cells express p75 as the predominant IL-2 receptor. IL-2-dependent tyrosine phosphorylation was observed in both cell lines and the concentrations of IL-2 needed to stimulate this phosphorylation were similar to that required for binding to the p75 receptor. Antibodies that inhibit binding of IL-2 to p55 had no effect on...Continue Reading

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Mentioned in this Paper

IL2
Interleukin 2 Receptor, Alpha
Protein Phosphorylation
Hairy Cell Leukemia
Tetraiodofluorescein
Fluorescein (5 or 6)-Isothiocyanate
Leukemic Cell
Tyrosine Phosphorylation
Fluorochromes
Tyrosine Measurement

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