Heat shock protein 90 kDa beta member 1 (GRP94) (GRP94)

Heat shock protein 90 kDa beta member 1, commonly known as GRP94 (Glucose-Regulated Protein 94), is the endoplasmic reticulum (ER)-resident member of the HSP90 family of molecular chaperones [UniProt P14625]. It plays a critical role in the folding and assembly of specific secreted and membrane proteins, including Toll-like receptors (TLRs), integrins, and insulin-like growth factors (IGFs) [PMID: 23435371]. Unlike the cytosolic HSP90 isoforms, GRP94 has a more restricted set of client proteins, which makes it a highly specific target for therapeutic intervention in diseases where these clients are overexpressed or dysregulated [PMID: 25111034]. In oncology, GRP94 is frequently upregulated to support the folding of proteins essential for tumor growth, metastasis, and immune evasion [PMID: 30249617]. Therapeutic strategies primarily involve small-molecule inhibitors that target the N-terminal ATPase domain, thereby disrupting its chaperone function and leading to the degradation of its client proteins [PMID: 24631653]. Selective inhibition of GRP94 is currently being explored to minimize the systemic toxicities associated with pan-HSP90 inhibitors, such as hepatotoxicity and visual disturbances [PMID: 26865469].

Other names

EndoplasminGP96TRA1ERp99Glucose-regulated protein 94 kDaTumor rejection antigen 1HSP90B1

Inhibition of the N-terminal ATPase domain to prevent the conformational maturation and folding of client proteins, leading to their degradation via the ubiquitin-proteasome pathway [PMID: 24631653, PMID: 23435371].