2 H(+) + H2O + urea = CO2 + 2 NH4(+) Binds 2 nickel ions per subunit. Nitrogen metabolism; urea degradation; CO(2) and NH(3) from urea (urease route): step 1/1. Heterotrimer of UreA (gamma), UreB (beta) and UreC (alpha) subunits. Three heterotrimers associate to form the active enzyme (By similarity). The probable operon is induced by urea. Belongs to the metallo-dependent hydrolases superfamily. Urease alpha subunit family.