Travels with carnitine palmitoyltransferase I: from liver to germ cell with stops in between

Although malonyl-CoA was first recognized as a central component in the regulation of hepatic ketogenesis, its inhibitory effect on mitochondrial carnitine palmitoyltransferase I (CPT I) has come to be viewed as a key element in fuel sensing in a variety of body tissues. This broadening role of the malonyl-CoA/CPT I partnership in the control of glucose and fatty acid metabolism, as well as current understanding of structure-function relationships surrounding the CPT proteins, are outlined. The intriguing question of whether CPT I has an important function in sperm development is also addressed briefly.