Baird M L, Garber E D
Biochem Genet. 1981 Dec;19(11-12):1101-14. doi: 10.1007/BF00484568.
Two complementing loci in different linkage groups of the basidiomycete Ustilago violacea are involved in urease activity: a structural one (ure-1) and a second inferred to involve a permease (ure-2) locus. Two types of complementing mutations occur in the structural locus: null activity (ure-la) and obviously reduced activity (ure-1b). The ure-2 mutants lacked urease activity in vivo on the phenol red-urea est medium, but gave extracts with wild-type activity. Extracts from wild-type strains gave one site of urease activity after polyacrylamide gel electrophoresis. A number of ure-1b mutants and activity revertants from ure-1a mutants yielded electrophoretically variant urease sites. The results are discussed in terms of enzyme polymorphism in haploid eukaryotes by one (missense) or two (null, then missense) mutations.
一个是结构基因座（ure-1），另一个推测涉及通透酶（ure-2）基因座。结构基因座中发生两种类型的互补突变：无活性（ure-1a）和明显降低的活性（ure-1b）。ure-2突变体在酚红-尿素培养基上体内缺乏脲酶活性，但提取物具有野生型活性。野生型菌株的提取物在聚丙烯酰胺凝胶电泳后产生一个脲酶活性位点。许多ure-1b突变体和ure-1a突变体的活性回复体产生了电泳变异的脲酶位点。通过一个（错义）或两个（无义，然后错义）突变，就单倍体真核生物中的酶多态性对结果进行了讨论。
