STAT 1, phosphorylated (Ser727) (Signal Transducer and Activator of Transcription 1-alpha/beta, Transcription Factor ISGF-3 Components p91/p84, STAT1)

STATs (signal transducers and activators of transcription) were originally discovered as two proteins (STAT1 and STAT2) which were involved in interferon alpha (IFN alpha) and IFN gamma signal transduction. Since then, several additional STAT proteins have been identified (STAT3, 4, 5a, 5b, and 6). STATs undergo tyrosine phosphorylation in response to growth factor or cytokine signaling. This phosphorylation results in dimerization and translocation of STAT proteins to the nucleus. In some cases this process is mediated by JAK Kinases (Janus Kinases 1, 2, and 3). For maximum activation of these proteins, phosphorylation at specific tyrosine and serine residues may be required in STAT1 alpha, 3, 4, and 5. Specific functions of the STAT proteins are poorly defined at this time. They are thought to be involved in a variety of systems including antiviral responses and cell transformation. STAT1 deficient knock-out mice are unable to induce IFN regulated genes and are extremely susceptible to viral diseases. After phosphorylation, STAT1 and STAT2 form heterodimers that function as more potent inducers of transcription than the STAT1 homodimer. STAT1 is known to associate with the transcription factors p48, Sp1, and p300. STAT1 is activated by peptide hormones, growth factors and cytokines, particularly cytokines of the interferon family. STAT1 alpha and STAT1 beta isoforms arise by alternative splicing of a single gene. The only difference between the two proteins is that STAT1 beta lacks 38 carboxy terminal amino acids. Contained within these 38 terminal aa of STAT1 alpha is a critical serine residue (Ser 727) whose phosphorylation is required for maximal transcription activity induced by IFN gamma. Applications: Suitable for use in Western Blot and Immunohistochemistry. Other applications not tested. Recommended Dilution: Western Blot:1:500-1:1,000 Immunohistochemistry:1:50-1:100 Optimal dilutions to be determined by the researcher. Storage and Stability: May be stored at 4 degrees C for short-term only. Aliquot to avoid repeated freezing and thawing. Store at -20 degrees C. Aliquots are stable for at least 12 months. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap.