Structural domains of interleukin-2 receptor beta critical for signal transduction: kinase association and nuclear complex-formation

• Published in: Biochemical journal 1995-02, Vol.306 ( Pt 1) (1), p.217-224
• Main Authors: Howard, O M, Kirken, R A, Garcia, G G, Hackett, R H, Farrar, W L
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Base Sequence; Cell Division; Cell Line; Cell Nucleus - metabolism; Gene Deletion; Humans; Lymphocytes; Mice; Molecular Sequence Data; Mutagenesis; Phosphotyrosine; Plasmids; Protein Kinases - metabolism; Receptors, Interleukin-2 - chemistry; Receptors, Interleukin-2 - genetics; Receptors, Interleukin-2 - metabolism; Signal Transduction; Structure-Activity Relationship; Transfection; Tyrosine - analogs & derivatives; Tyrosine - analysis; Tyrosine - metabolism
• ISSN: 0264-6021; 1470-8728
• DOI: 10.1042/bj3060217

The structural domains of interleukin-2 receptor beta (IL-2R beta) were examined, characterizing the protein domains, associated phosphoproteins and nuclear complexes of IL-2-induced signal transduction. A series of IL-2R beta cytoplasmic deletion mutants were constructed and transfected into a murine pre-B-cell line, Ba/F3. The proliferative response of characterized clones was determined. A minimal linear cytoplasmic sequence required for proliferation and a sequence motif (PQPLXP) needed along with Box1-Box2 for IL-2-induced proliferation were identified. Anti-phosphotyrosine Western-blot analysis of a stimulated biologically active clone showed several IL-2-induced tyrosylphosphorylated proteins with molecular masses ranging from 45 to 116 kDa. In vitro kinase studies of biologically active clone-receptor complexes showed a 116 kDa protein (p116) to be the major tyrosine-phosphorylated component. The presence of the p116 kinase in the receptor complex correlates with IL-2-induced proliferation. An IL-2-inducible p116 kinase has recently been characterized as a Jak kinase family member and named Jak3. Nuclear complexes were formed with the GRR oligomer only when the IL-2R beta mutant supported proliferation. This led us to conclude that Box1-Box2 and PQPLXP motifs associate with Jak3 and that this association is an essential element in the IL-2 signal-transduction pathway culminating in the formation of a nuclear complex.