The function of Ensembl gene identifier ENSG00000204922 (UQCC3, ubiquinol-cytochrome c reductase complex assembly factor 3) is as follows. Required for the assembly of the ubiquinol-cytochrome c reductase complex (mitochondrial respiratory chain complex III or cytochrome b-c1 complex), mediating cytochrome b recruitment and probably stabilization within the complex. Thereby, plays an important role in ATP production by mitochondria. Cardiolipin-binding protein, it may also control the cardiolipin composition of mitochondria membranes and their morphology. {ECO:0000269|PubMed:25008109, ECO:0000269|PubMed:25605331}.