Anti-HSF1 (phospho-S303) Antibody

Raised in rabbit against a phosphopeptide epitope centred on serine 303 of human Heat Shock Factor 1 (HSF1), this unconjugated polyclonal antibody from Antibodies.com selectively detects the phosphorylated, rather than the total, pool of HSF1. The site at S303 is a regulatory modification: under basal conditions it is targeted by kinases such as CK2 and members of the MAPK cascade, and the resulting phospho-S303 signal is widely used as a marker of HSF1's repressed, cytoplasmic state versus its activated, trimeric, DNA-binding form.

The reagent is supplied at 1 mg/ml in phosphate buffered saline (pH approximately 7.2) with 0.05% sodium azide as preservative, and is validated for western blot, immunohistochemistry and immunofluorescence on human, mouse and rat samples. A 100 µl pack size is sufficient for multiple replicate blots or a panel of stained sections, and the unconjugated format leaves the choice of HRP, biotin or fluorophore secondary reagents to the end user.

Typical uses include tracking the cellular response to thermal, oxidative or proteotoxic stress, profiling HSF1 regulation in cancer cell lines where the heat shock programme is rewired, and distinguishing kinase-driven changes in HSF1 phosphorylation status from changes in total HSF1 abundance. Because the antibody is phospho-specific, it is most informative when run alongside a total HSF1 antibody and an appropriate loading control.