Rabbit polyclonal antibody to CD123 (Q192)

Interleukin~3, or IL~3, is a pleiotropic cytokine that is primarily secreted by activated T lymphocytes and stimulates the proliferation and differentiation of hematopoietic cells. IL~3 exerts its biological effects through a receptor which consists of a ligand~specific α subunit (IL~3Rα) and a signal transducing β subunit (IL~3Rβ) common to the IL~3/IL~5/GM~CSF receptors. The α subunits are low~affinity ligand~binding proteins while the β subunits do not themselves bind ligand, but are required for high affinity binding by the α subunits. The mouse IL~3 receptor has two distinct β subunits, one that functions only in IL~3~mediated cell signaling and a second that is shared with IL~5 and GM~CSF. The murine β subunits are 91% homologous at the amino acid level but only 56% homologous to the human β subunit. The carboxy~terminus of the β subunit has been shown to be necessary for activation of the MAP kinase signaling pathway. Although the IL~3 receptor has no intrinsic kinase activity, stimulation with IL~3 leads to tyrosine phosphorylation of the JAK/Tyk 2 family member, JAK2, which in turn activates and causes nuclear translocation of Stat5a and Stat5b.