STEAP4 is an integral membrane metalloreductase that functions as a key regulator of cellular iron and copper homeostasis and metabolic function 1. The protein mediates NADPH-dependent reduction of Fe(3+) chelates and Cu(2+) ions through sequential transmembrane electron transfer involving FAD and heme cofactors 2. STEAP4 plays a crucial role in systemic metabolic homeostasis by integrating inflammatory and metabolic responses 3. Expression is significantly downregulated in adipose tissue of obese children and adults, correlating negatively with blood pressure, lipid levels, glucose, and inflammatory markers like IL-6 and TNF-α 45. The protein demonstrates tissue-specific expression patterns, with higher levels in visceral versus subcutaneous adipose tissue that decrease with increasing BMI 5. STEAP4 promotes cell survival and proliferation through AKT/mTOR signaling while regulating oxidative stress responses 6. Recent studies indicate STEAP4 can contribute to cuproptosis, a copper-dependent cell death mechanism, when upregulated by transcription factors like FOXO1 7. Genome-wide association studies have linked STEAP4 mutations to metabolic disorders including obesity, metabolic syndrome, and type 2 diabetes 1.