Heat shock protein HSP 90-beta

HSP90AB1 encodes Heat Shock Protein 90-beta (HSP90), a molecular chaperone that promotes maturation, structural maintenance, and regulation of specific target proteins involved in cell cycle control and signal transduction (UniProt: P08238). The protein cycles through an ATP-dependent functional process that induces conformational changes in client proteins, activating them through interactions with various co-chaperones. Beyond chaperoning, HSP90 regulates transcription machinery by modulating transcription factor levels, epigenetic modifiers, and histone dynamics.

HSP90 operates broadly across cellular pathways including TGF-beta signaling, cell differentiation, STAT1 phosphorylation, and endoplasmic reticulum-to-Golgi cargo translocation (UniProt: P08238). The protein is implicated in responses to microbial infection and has no designated disease category in the UniProt record.

In Alzheimer's Disease, HSP90AB1 shows ambiguous directional change across subcellular fractions in post-mortem AD brain compared to age-matched controls (Chaparral AD proteomics). The mean log2 fold-change is −0.39, indicating overall modest downregulation, though the ambiguous direction tag reflects divergent regulation across the analyzed cellular fractions. This modest shift suggests HSP90 may experience compartment-specific dysregulation in AD pathology.