ATCASE

ATCase: translation

(= aspartate transcarbamylase)

Enzyme (EC 2.1.3.2) that catalyses the first step in pyrimidine biosynthesis, condensation of aspartate and carbamyl phosphate. Positively allosterically regulated by ATP and negatively by CTP; classic example of an allosterically regulated enzyme. Bacterial ATCases exist in three forms: class A (ca 450-500 kD), class B (ca 300 kD) and class C (ca 100 kD).