The regulation of urea amidolyase of Saccharomyces cerevisiae: mating type influence on a constitutivity mutation acting in cis.

Summary Constitutivity for the synthesis of the urea amidolyase bienzymatic complex is obtained by dur0^hmutations located in the regulatory genetic region adjacent to the dur1, dur2 gene cluster. The dur0^hmutations act only in cis and are a new case of cis effect strongly cancelled in /a diploid, similar to cargA⁺0^hmutation shown previously to lead to arginase constitutivity. Illegitimate diploids do not show such a cancellation of constitutivity.The constitutivity produced by dur0^hmutation comprises the process of induction and the release of the glutamine effect. It does not impair the NH₄⁺effect.