Cytochrome b561 family member D2 (CYB561D2)

Cytochrome b561 family member D2 (CYB561D2) is a transmembrane heme-containing protein that functions primarily as a monodehydroascorbate reductase and iron reductase, enabling electron transfer from ascorbate in the cytoplasm to ferric ions and monodehydroascorbate in the endoplasmic reticulum lumen. It regulates cellular ascorbate and iron homeostasis and is implicated in redox balance and immune modulation via STAT3 pathway activation in tumors, particularly gliomas. CYB561D2 acts as a putative tumor suppressor when deleted or downregulated (notably in lung cancer), but its upregulation in glioma promotes tumor aggression and immunosuppression through induction of PD-L1 and related genes. Located on human chromosome 3p21.3, a region frequently deleted in cancer, its expression level serves as a biomarker for prognosis and may present a future pathway for therapeutic intervention, although targeted drugs are still investigational.

Other names

101F6LUCA12.2TSP10TSCytbCytochrome b561 domain-containing protein 2Putative tumor suppressor protein 101F6transmembrane ascorbate ferrireductasetumor suppressor cytochrome b561XXcos-LUCA11.4

Electron transport from cytoplasmic ascorbate across endoplasmic reticulum membrane to reduce lumenal monodehydroascorbate and ferric ions (Fe³⁺); modulation of STAT3 signaling and downstream immune regulatory genes such as PD-L1, CCL2, TDO2 in tumor cells