Scientists observed the thermogenic activity in brown adipose tissue, which eventually led to the discovery of UCP1, initially known as "Uncoupling Protein". The brown tissue revealed elevated levels of mitochondria respiration and another respiration not coupled to ATP synthesis, which symbolized strong thermogenic activity. UCP1 was the protein discovered responsible for activating a proton pathway that was not coupled to ADP phosphorylation (ordinarily done through ATP Synthase).