Functional characterization of UCP1 in mammalian HEK293 cells excludes mitochondrial uncoupling artefacts and reveals no contribution to basal proton leak

► Characterization of a novel mammalian cell system to test the function of UCP1. ► Mouse UCP1 does not contribute to mitochondrial basal proton leak. ► Quantification and meta-analysis of UCP1 catalytic centre activities ► Mathematical approach to the relation between proton leak and membrane potential