Regulation of the interleukin 2 receptor complex tyrosine kinase activity in vitro.
Interleukin 2 (IL-2) has been shown to stimulate tyrosine phosphorylation of a number of proteins requiring only the p75 beta chain of the IL-2 receptor. Unlike the receptors for epidermal growth factor, insulin, and other growth factors, the p55-alpha and p75-beta chains of the IL-2 receptor have no tyrosine protein kinase domain suggesting that the IL-2 receptor complex activates protein kinases by a unique mechanism. The activation of tyrosine kinases by IL-2 in situ was studied and using a novel methodology has shown tyrosine kinase activity associated with the purified IL-2R complex in vitro. IL-2 stimulated the in situ tyrosine phosphorylation of 97 kDa and 58 kDa proteins which bound to poly(Glu,Tyr)4:1, a substrate for tyrosine protein kinases, suggesting these proteins had characteristics found in almost all tyrosine kinases. IL-2 was found to stimulate tyrosine protein kinase activity in receptor extracts partially purified from human T lymphocytes and the YT cell line. Biotinylated IL-2 was used to precipitate the high-affinity-receptor complex and phosphoproteins associated with it. The data indicated that the 97-kDa and 58-kDa phosphotyrosyl proteins were tightly associated with the IL-2 receptor complex. These proteins were phosphorylated on tyrosine residues by IL-2 stimulation of intact cells and ligand treatment of in vitro receptor extracts. Furthermore, the 97-kDa and 58-kDa proteins were found in streptavidin-agarose/biotinylated IL-2 purified receptor preparations and showed high affinity for tyrosine kinase substrate support matrixes. The experiments suggest that these two proteins are potential candidates for tyrosine kinases involved in the IL-2R complex signal transduction process.
Michiel
D F
DF
Laboratory of Molecular Immunoregulation, National Cancer Institute, Frederick Cancer Research and Development Center, MD 21702-1201.
Garcia
G G
GG
Evans
G A
GA
Farrar
W L
WL
D002460:Cell Line; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007376:Interleukin-2 / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D015375:Receptors, Interleukin-2 / Q000378:metabolism*; D012995:Solubility; D013601:T-Lymphocytes / Q000166:cytology / Q000378:metabolism
D007376:Interleukin-2; D010750:Phosphoproteins; D015375:Receptors, Interleukin-2; D011505:Protein-Tyrosine Kinases