Description: This 4LURPIE monoclonal antibody recognizes human and mouse signal transducer and activator of transcription 4 (STAT4) when phosphorylated on tyrosine 693 (Y693). STAT proteins are activated by ligand binding to cytokine receptors that associate with Janus kinase (JAK) family members. Following their phosphorylation by JAK proteins, STAT proteins translocate to the nucleus where they bind to DNA and regulate transcription of specific genes in a cell type- and cytokine-specific manner. STAT4 is activated by IL-12 or type 1 IFN (IFN alpha, IFN beta). STAT4 is required for optimal Th1 differentiation in vivo. Interestingly, although IFN alpha can lead to phosphorylation of STAT4 in mouse T cells, the phosphorylation is much weaker than that induced by IL-12 and is transient. Thus, IFN alpha phosphorylation of STAT4 does not contribute to STAT4-mediated Th1 development or IFN gamma production by Th1 cells in mice. In contrast, IFN alpha does promote Th1 development and function of human CD4+ T cells. Specificity of this 4LURPIE clone was determined by ELISA and flow cytometry. Applications Reported: This 4LURPIE antibody has been reported for use in intracellular staining followed by flow cytometric analysis. Applications Tested: This 4LURPIE antibody has been pre-titrated and tested by intracellular staining followed by flow cytometric analysis of stimulated normal human peripheral blood cells. This can be used at 5 µL (0.25 µg) per test.A test is defined as the amount (µg) of antibody that will stain a cell sample in a final volume of 100 µL. Cell number should be determined empirically but can range from 10^5 to 10^8 cells/test. Staining Protocol: We recommend using Protocol C: Two-step protocol: Fixation/Methanol. Protocol A: Two-step protocol: intracellular (cytoplasmic) proteins and Protocol B: One-step protocol: intracellular (nuclear) proteins cannot be used. All Protocols can be found in the Flow Cytometry Protocols: "Staining Intracellular Antigens for Flow Cytometry Protocol" located in the Best Protocols Section under the Resources tab online. Excitation: 488-561 nm; Emission: 578 nm; Laser: Blue Laser, Green Laser, Yellow-Green Laser. Filtration: 0.2 µm post-manufacturing filtered. STAT4 was originally identified using degenerate primers complementary to sequences encoding conserved regions of other STAT proteins. The STAT4 protein is most similar to STAT1 (52%) and STAT3 (47%). Functionally, STAT4 is similar to other STAT family members in that it can be tyrosine phosphorylated by Jak1 or Jak2. STAT4 forms homodimers and heterodimers with related STAT family members. Tyrosine phosphorylated STAT4 can bind the IFN-gamma activated site (GAS). Serine phosphorylation of STAT is also required for maximal transcriptional activity. STAT4 expression is restricted to the thymus, spleen and testis. Until recently the cytokine(s) responsible for activation of STAT4 had not been identified. STAT4 is now known to be activated by the cytokine interleukin 12 (IL-12). IL-12 is required for the T-cell independent induction of IFN-gamma which is a key step in the initial suppression of bacterial and parasitic infections. In addition, IL-12 is required for the development of a Th1 response which is necessary for effective host defense against intracellular pathogens. STAT4-deficient mice display impaired IL-12 development of Th1 cells and enhanced development of Th2 cells. A recent study in mouse has shown that in response to viral infection IFN-a/b activation of STAT4 is required for IFN-g production.
|4° C, store in dark, DO NOT FREEZE!|
|PBS with 0.1% gelatin, 0.2% BSA and 0.09% sodium azide; pH 7.2|
For Research Use Only.
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