Anti-Heat Shock Factor 1 (HSF1, Heat Shock Factor Protein 1, HSF 1, Heat Shock Transcription Factor

HSF1 belongs to a family of Heat Shock transcription Factors (HSFs) that bind to highly conserved heat shock elements (HSEs) in the promoter regions of heat shock genes and regulate the expression of heat shock proteins (Hsps). Multiple HSFs exist in higher eukaryotes whereas yeast and Drosophila have only a single HSF. HSF1, HSF2, HSF3 have been reported in chicken, HSF1 and HSF2 in mouse and HSF1, HSF2, and HSF4 in human. Most HSFs have several common functional motifs whose amino acid sequences are highly conserved. At the N-terminus of all HSFs there is a DNA binding domain essential for binding to the HSE. Hydrophobic repeats located adjacent to the DNA binding domain are essential for the formation of active trimers which enable all HSFs to specifically bind to DNA. Another short hydrophobic repeat located towards the C-terminal region of most HSFs is thought to be necessary for suppression of trimerization except in the case of yeast HSF and human HSF4. The mouse HSF1 exists as two isoforms which arise from alternative splicing of the HSF1 pre-mRNA. In higher eukaryotes, HSF1 is predominantly found in a diffuse cytoplasmic and nuclear distribution in unstressed cells. On exposure to heat shock and other stresses, HSF1 localizes within seconds to discrete nuclear granules and on recovery from stress, HSF1 rapidly dissipates from the stress granules to a diffuse nucleoplasmic distribution. Similar to HSF1, murine HSF2 also exist as two isoforms, the smaller HSF2-beta isoform and the longer HSF2-alpha which has been shown to be more transcriptionally active. Constitutive binding of HSF2 to HSE has been found with spermatogenic cells post-implantation embryos and embryonal carcinoma cells in mouse and these observations suggest that HFS2 may have roles in differentiation and development. 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°C for short-term only. Aliquot to avoid repeated freezing and thawing. Store at -20°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.