<p>There are four different enzymes that share a similar catalytic mechanism which involves the phosphorylation by ATP (or GTP) of a specific histidine residue in the active site. These enzymes are: ATP citrate-lyase (<db_xref db="EC" dbkey="4.1.3.8"/>) [<cite idref="PUB00001411"/>], the primary enzyme responsible for the synthesis of cytosolic acetyl-CoA in many tissues, catalyzes the formation of acetyl-CoA and oxaloacetate from citrate and CoA with the concomitant hydrolysis of ATP to ADP and phosphate. ATP-citrate lyase is a tetramer of identical subunits; Succinyl-CoA ligase (GDP-forming) (<db_xref db="EC" dbkey="6.2.1.4"/>) [<cite idref="PUB00005004"/>] is a mitochondrial enzyme that catalyzes the substrate level phosphorylation step of the tricarboxylic acid cycle: the formation of succinyl-CoA from succinate with a concomitant hydrolysis of GTP to GDP and phosphate. This enzyme is a dimer composed of an alpha and a beta subunits; Succinyl-CoA ligase (ADP-forming) (<db_xref db="EC" dbkey="6.2.1.5"/>) [<cite idref="PUB00000280"/>] is a bacterial enzyme that during aerobic metabolism functions in the citric acid cycle, coupling the hydrolysis of succinyl-CoA to the synthesis of ATP. It can also function in the other direction for anabolic purposes. This enzyme is a tetramer composed of two alpha and two beta subunits; and Malate-CoA ligase (<db_xref db="EC" dbkey="6.2.1.9"/>) (malyl-CoA synthetase) [<cite idref="PUB00002257"/>], is a bacterial enzyme that forms malyl-CoA from malate and CoA with the concomitant hydrolysis of ATP to ADP and phosphate. Malate-CoA ligase is composed of two different subunits.</p><p>This pattern, which is located some 50 residues to the C-terminal of <db_xref db="INTERPRO" dbkey="IPR005810"/>, includes the active site phosphorylated histidine residue. </p> ATP-citrate lyase/succinyl-CoA ligase, active site