Intracytoplasmic phosphorylation sites of Tac antigen (p55) are not essential for the conformation, function, and regulation of the human interleukin 2 receptor.
Tac antigen, the receptor for human interleukin 2 (IL-2), contains in its intracytoplasmic region a serine residue (Ser-247) that is seemingly the predominant site of protein kinase C-mediated phosphorylation. A number of studies on growth factor receptors have suggested the importance of phosphorylation in receptor structure, function, and regulation. In this study, we generated site-directed mutations in the Tac antigen cDNA to generate mutant receptors in which Ser-247 or Thr-250, a probable site of minor phosphorylation, was replaced with another amino acid that is not accessible to phosphorylation. Study of the expression of these mutant genes in a T-lymphoid cell line has provided no evidence as to the essential role of the above-mentioned residues in determining the degree of receptor affinity, its ability for signal transduction, and phorbol ester-mediated regulation of the receptor. Our results strongly suggest the existence of an IL-2 receptor "complex" in which the Tac antigen is associated with another molecule(s) that is involved in receptor structure, function, and regulation.
D000595:Amino Acid Sequence; D003593:Cytoplasm / Q000502:physiology; D006801:Humans; D007376:Interleukin-2 / Q000502:physiology*; D008565:Membrane Proteins / Q000502:physiology; D009154:Mutation; D010750:Phosphoproteins / Q000502:physiology; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D011971:Receptors, Immunologic / Q000235:genetics / Q000502:physiology*; D015375:Receptors, Interleukin-2; D013329:Structure-Activity Relationship; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D007376:Interleukin-2; D008565:Membrane Proteins; D010750:Phosphoproteins; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate