Mediating the functional connection between transcription factors and the general transcription apparatus are the coactivators. Coactivator refers to a protein or protein complex that increases the rate of transcription by interacting with transcription factors but does not itself bind to DNA in a sequence-specific manner. Peroxisome proliferator–activated receptor-γ coactivator-1 (PGC-1s) are proteins that enhance the transcriptional activity of transcription factors through direct protein-protein interactions. PGC-1α serves as an inducible coregulator in the control of energy homeostasis, and its expression is induced rapidly by physiological conditions known to increase the demand for mitochondrial ATP production such as cold exposure, exercise, and fasting. It has been shown to regulate adaptive thermogenesis, mitochondrial biogenesis, glucose and fatty acid metabolism, the peripheral circadian clock, fiber-type switching in skeletal muscle, and heart development.[1][2][3]