STEAP1 Flag&His Tag Full Length Protein, Human (Detergent)

STEAP1 is a member of the STEAP family and is highly expressed in multiple cancers, including prostate, bladder, colorectal, lung, ovarian, and breast cancers and Ewing sarcoma, with limited expression in normal tissues, making it an attractive diagnostic and therapeutic target. Structurally, STEAP1 is a six-transmembrane protein that assembles into homotrimers, with each protomer binding a single b-type heme coordinated by conserved histidines. Unlike STEAP2–STEAP4, STEAP1 lacks an N-terminal cytosolic oxidoreductase domain (OxRD) and therefore does not independently support NADPH-dependent ferric reductase activity in cells. Nevertheless, its transmembrane domain is redox-competent: reduced STEAP1 can reduce Fe³⁺/Cu²⁺ complexes and O₂, and STEAP1 can accept electrons from reduced FAD or cytochrome b₅ reductase/NADH. STEAP1 also forms heterotrimers with STEAP2 and may utilize reduced FAD generated by STEAP2. Fusion of the STEAP1 transmembrane domain to the STEAP4 OxRD restores cellular ferric reductase activity, indicating that STEAP1 functions as a transmembrane electron-transfer module requiring an external electron-donating partner.

Therapeutically, STEAP1 is targeted by the monoclonal antibody mAb120.545 and its humanized derivatives. Clinically, humanized mAb120.545 variants have been developed as antibody–drug conjugates (e.g., DSTP3086S/vandortuzumab vedotin) and as ⁸⁹Zr-labeled immuno-PET agents (e.g., MSTP2109A) for prostate cancer imaging. In addition, STEAP1-derived peptides are immunogenic and can be recognized by cytotoxic T lymphocytes, supporting STEAP1 as a candidate for vaccine-based immunotherapy.