There are five UCP homologs known in mammals. While each of these performs unique functions, certain functions are performed by several of the homologs. The homologs are as follows:
*UCP1, also known as thermogenin or SLC25A7
*UCP2, also known as SLC25A8
*UCP3, also known as SLC25A9
*UCP4, also known as SLC25A27
*UCP5, also known as SLC25A14