Integral membrane protein that functions as a NADPH-dependent ferric-chelate reductase, using NADPH from one side of the membrane to reduce a Fe(3+) chelate that is bound on the other side of the membrane. Mediates sequential transmembrane electron transfer from NADPH to FAD and onto heme, and finally to the Fe(3+) chelate . Can also reduce Cu(2+) to Cu(1+) (By similarity). Plays a role in systemic metabolic homeostasis, integrating inflammatory and metabolic responses (By similarity). Associated with obesity and insulin-resistance (, ). Involved in inflammatory arthritis, through the regulation of inflammatory cytokines . Inhibits anchorage-independent cell proliferation .
Subcellular locations: Cell membrane, Golgi apparatus membrane, Early endosome membrane
Ubiquitous. Highly expressed in adipose tissue. Expressed in placenta, lung, heart and prostate. Detected at lower levels in liver, skeletal muscle, pancreas, testis and small intestine. Highly expressed in joints of patients with rheumatoid arthritis and localized with CD68 cells, a marker for macrophages.