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 Note: - initially thought to have tumor suppressor function in prostate cancer; however, probably not

General

flavoprotein metalloprotein oxidoreductase metalloreductase STEAP (six-transmembrane epithelial antigen of prostate, STEAP)

Properties

SIZE: MW = 55 kD entity length = 488 aa COMPARTMENT: cell nucleus MOTIF: cytoplasmic domain {1-207} MOTIF: Ser phosphorylation site {S20} transmembrane domain {208-228} exoplasmic loop {229-258} MOTIF: N-glycosylation site {N256} transmembrane domain {259-279} cytoplasmic loop {280-304} transmembrane domain {305-325} MOTIF: Iron [Fe]-binding site SITE: 316-316 exoplasmic loop {326-358} transmembrane domain {359-379} cytoplasmic loop {380-390} transmembrane domain {391-411} MOTIF: Iron [Fe]-binding site SITE: 409-409 exoplasmic loop {412-433} transmembrane domain {434-454} cytoplasmic domain {455-488}

References

UniProt :accession Q658P3