UQCRB is a nuclear-encoded component of the ubiquinol-cytochrome c oxidoreductase (complex III) in the mitochondrial electron transport chain. It functions as part of the Q cycle, catalyzing electron transfer from ubiquinol to cytochrome c while coupling this redox reaction to proton translocation across the inner mitochondrial membrane, thereby driving oxidative phosphorylation and ATP synthesis. UQCRB expression is subject to translational control during metabolic reprogramming; for instance, downregulation of UQCRB by the NAT10 acetyl-transferase suppresses mitochondrial respiration and enhances glycolytic capacity in cardiomyocytes during heart regeneration 1. The gene is located on chromosome 8 as a single copy 23, and its promoter region contains regulatory elements shared with other mitochondrial respiratory genes 4. Clinically, UQCRB dysregulation is associated with colorectal carcinoma, where upregulation in tumor tissues correlates with disease stage and copy number variation 5. Elevated UQCRB expression also links to elevated circulating miR-4435, a potential cancer biomarker 6. Recent work identifies UQCRB as a host factor in Ebola virus RNA replication, and small-molecule UQCRB inhibition reduces viral infection in vitro 7. A 5-gene peripheral blood signature including UQCRB predicts immunotherapy response in non-small cell lung cancer, stratifying patients into responders and non-responders with high accuracy 8.