Detection of Human, Mouse, and Rat STI1 by Western Blot. Western blot shows lysates of U2OS human osteosarcoma cell line, NIH‑3T3 mouse embryonic fibroblast cell line, and PC‑12 rat adrenal pheochromocytoma cell line. PVDF membrane was probed with 0.1 µg/mL of Sheep Anti-Human/Mouse/Rat STI1 Antigen Affinity-purified Polyclonal Antibody (Catalog # AF7337) followed by HRP-conjugated Anti-Sheep IgG Secondary Antibody (Catalog # HAF016). A specific band was detected for STI1 at approximately 62 kDa (as indicated). This experiment was conducted under reducing conditions and using Immunoblot Buffer Group 1.
Preparation and Storage
Sterile PBS to a final concentration of 0.2 mg/mL.
The product is shipped at ambient temperature. Upon receipt, store it immediately at the temperature recommended below. *Small pack size (SP) is shipped with polar packs. Upon receipt, store it immediately at -20 to -70 °C
Stability & Storage
Use a manual defrost freezer and avoid repeated freeze-thaw cycles.
12 months from date of receipt, -20 to -70 °C as supplied.
1 month, 2 to 8 °C under sterile conditions after reconstitution.
6 months, -20 to -70 °C under sterile conditions after reconstitution.
STI1 (Stress-induced phosphoprotein 1; also HOP and STIP-1) is a 60-62 kDa member of the STI-1 family of proteins. It is widely expressed, and participates in the formation of functional steroid hormone receptor complexes. Steroid receptors (SR) require proper folding to achieve optimal conformation. In the case of progesterone and glucocorticoid receptors, interaction with chaperones hsp70 and hsp90 facilitates this folding. STI1 is not a chaperone, but a mediator of SR-hsp70-hsp90 interaction. STI1 first binds dimeric hsp90. This trimer then interacts with a SR-(monomeric)hsp70-ADP protein heterodimer to form a SR-hsp70-STI1-hsp90 pentamer that subsequently dissociates into a mature hsp90-SR complex. The STI1-hsp90 complex is also found extracellularly and may contribute to MMP-2 activation. Human STI1 is 543 amino acids (aa) in length. It contains an initial N-terminal TPR domain (aa 4-105) that binds to hsp70, followed by a second TPR domain (aa 225-461) that binds to dimeric hsp90. There are at least 10 acetylated Lys residues plus four utilized phosphorylation sites. Zone potential isoform variant is reported that contains a 48 aa substitution for Gln3. Full-length human STI1 shares 97% aa sequence identity with mouse STI1.
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