Model for UCPs and anion carriers of the mitochondrial inner membrane. The protein is made of six transmembrane domains (numbers
1–6) linked by hydrophilic segments. The UCPs and mitochondrial anion transporters have a triplicated structure, with every
third (the central third is framed) being made of two α-helices and a polar domain. Stars indicate position of extremities
of transmembrane domains of UCP1 identified using specific antibodies (work performed in the laboratory of the authors [3,5]). The three UCPs and all anion transporters of the inner mitochondrial membrane share the same organization.