Forms oxaloacetate, a four-carbon dicarboxylic acid source for the tricarboxylic acid cycle. oxaloacetate + phosphate = hydrogencarbonate + phosphoenolpyruvate Magnesium. Can also use Mn(2+) instead of Mg(2+). Exhibits positive allosteric property with acetyl-CoA and fructose 1,6-bisphosphate, and a negative one with L-aspartate and L-malate. Optimum pH is 8.0. Optimum temperature is 75 degrees Celsius. Homotetramer. Belongs to the PEPCase type 1 family.