metalloreductase STEAP3 (six-transmembrane epithelial antigen of prostate 3, tumor suppressor-activated pathway protein 6, hTSAP6, pHyde, hpHyde, Dudulin-2, STEAP3, TSAP6)

Function

• endosomal ferrireductase required for efficient transferrin- dependent iron uptake in erythroid cells
• role in erythroid iron homeostasis by reducing Fe+3 to Fe+2
• reduces Cu+2 to Cu+, role in copper homeostasis (putative)
• uses NAD+ as acceptor (putative)
• acts downstream of p53/TP53 to interface apoptosis & cell cycle progression
• indirectly involved in exosome secretion by facilitating secretion of proteins including TCTP
• interacts with BNIP3L, MYT1 & TCTP

Cofactor: FAD (putative)

Structure

• belongs to the STEAP family
• contains 1 ferric oxidoreductase domain

Compartment

• endosome membrane
• localizes to vesicular-like structures at the plasma membrane & around the nucleus

Alternative splicing

named isoforms=4

Expression

• expressed in adult bone marrow, placenta, liver, skeletal muscle & pancreas
• down-regulated in hepatocellular carcinoma
• induced by p53/TP53

Notes

• initially thought to have tumor suppressor function in prostate cancer; however, probably not

More general terms

• metalloreductase STEAP
• flavoprotein
• oxidoreductase
• metalloprotein

Database

• UniProt: http://www.uniprot.org/uniprot/Q658P3.html