Citryl-CoA lyase (CCL), the C-terminal portion of the single-subunit type ATP-citrate lyase (ACL) and the C-terminal portion of the large subunit of the two-subunit type ACL. CCL cleaves citryl-CoA (CiCoA) to acetyl-CoA (AcCoA) and oxaloacetate (OAA). ACL catalyzes an ATP- and a CoA- dependant cleavage of citrate to form AcCoA and OAA in a multistep reaction, the final step of which is likely to involve the cleavage of CiCoA to generate AcCoA and OAA. In fungi, yeast, plants, and animals ACL is cytosolic and generates AcCoA for lipogenesis. ACL may be required for fruiting body maturation in the filamentous fungus Sordaria macrospore. In several groups of autotrophic prokaryotes and archaea, ACL carries out the citrate-cleavage reaction of the reductive tricarboxylic acid (rTCA) cycle. In the family Aquificaceae this latter reaction in the rTCA cycle is carried out via a two enzyme system the second enzyme of which is CCL; the first enzyme is citryl-CoA synthetase (CCS) which is not included in this group. Chlorobium limicola ACL is an example of a two-subunit type ACL. It is comprised of a large and a small subunit; it has been speculated that the large subunit arose from a fusion of the small subunit of the two subunit CCS with CCL. The small ACL subunit is a homolog of the larger CCS subunit. Mammalian ACL is of the single-subunit type and may have arisen from the two-subunit ACL by another gene fusion. Mammalian ACLs are homotetramers; the ACLs of C. limicola and Arabidopsis are a heterooctomers (alpha4beta4). In cancer cells there is a shift in energy metabolism to aerobic glycolysis, the glycolytic end product pyruvate enters a truncated TCA cycle generating citrate which is cleaved in the cytosol by ACL. Inhibiting ACL limits the in-vitro proliferation and survival of these cancer cells, reduces in vivo tumor growth, and induces differentiation.