Bifunctional enzyme that catalyzes both the deamination of dCTP to dUTP and the hydrolysis of dUTP to dUMP without releasing the toxic dUTP intermediate. dCTP + 2 H2O = diphosphate + dUMP + NH4(+) Inhibited by dTTP. Pyrimidine metabolism; dUMP biosynthesis; dUMP from dCTP: step 1/1. Homotrimer. Repressed by both deoxycytidine and thymidine. Belongs to the dCTP deaminase family.