STEAP1 notes

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Notes compiled from UniProt Q9UHE8 and cached publications.

Structure / topology

• Six-TM protein with intracellular N- and C-termini; PMID:10588738.
• Cryo-EM: homotrimer; heme b in TMD at the extracellular leaflet; mAb120.545 Fabs bind extracellular helices PMID:32409586.
• Lacks the N-terminal cytoplasmic F420H2:NADP+ oxidoreductase (FNO)-like NADPH-binding domain present in STEAP2-4.

Function

• PMID:32409586
• STEAP4-NADPH-domain/STEAP1 chimera reduces Fe(III); proposed to act as ferric reductase within STEAP heterotrimers (speculative) PMID:32409586.
• Heme b coordinated by H175 and H268 PMID:32409586.

Localization

• PMID:10588738; IHC at cell-cell junctions of prostate secretory epithelium.
• Plasma membrane by confocal (PMID:32409586). Endosome membrane only by similarity to mouse (UniProt ECO:0000250).
• Conclusion: plasma membrane (multi-pass), extracellular loops/helices exposed at cell surface (antibody/ADC target); N/C-termini cytoplasmic.