Klar A J, Fogel S
Proc Natl Acad Sci U S A. 1979 Sep;76(9):4539-43. doi: 10.1073/pnas.76.9.4539.
Yeast Saccharomyces cerevisiae may express an a or alpha mating type. These cells types may be interconverted as a consequence of heritable genetic alteractions at the mating type locus (MAT). According to the more general controlling element model [Oshima, U. & Takano, I. (1971) Genetics 67, 327--335] and the specific cassette model [Hicks, J., Strathern, J. & Herskowitz, I. (1977) in DNA Insertion Elements, Plasmids and Episomes, eds. Bukhari, A. I., Shapiro, J.A. & Adhya, S. L.(Cold Spring Harbor Laboratory, Cold Spring Harbor, NY), pp. 457--462], the regulatory information required for switching the MAT locus exists at two other loosely linked loci, HMa and HMalpha. Specifically, the HMa and HMalpha loci are proposed to carry silent alpha and silent a genes, respectively. According to these models, switching occurs when a replica of a silent gene replaces the resident information at the mating type locus and is thereby expressed. These models predict that mutations at the silent ("storage") loci would generate defective MAT loci subsequent to the switching process. Therefore, the behavior of HMalpha mutants during the mating type interconversion was investigated. The results demonstrate that defective MATa alleles are generated by switching the MATalpha locus in HMalpha mutants. Thus, the genetic information from HMalpha is transposed to the mating type locus. These results provide genetic evidence in support of these models.
酿酒酵母可以表达a或α交配型。由于交配型位点（MAT）处的可遗传基因改变，这些细胞类型可以相互转换。根据更通用的控制元件模型[大岛，U.和高野，I.（1971年）《遗传学》67卷，327 - 335页]和特定盒式模型[希克斯，J.、斯特拉瑟恩，J.和赫斯科维茨，I.（1977年）载于《DNA插入元件、质粒和附加体》，布哈里，A.I.、夏皮罗，J.A.和阿迪亚，S.L.编（冷泉港实验室，纽约冷泉港），第457 - 462页]，转换MAT位点所需的调控信息存在于另外两个松散连锁的位点，HMa和HMα。具体而言，提议HMa和HMα位点分别携带沉默的α基因和沉默的a基因。根据这些模型，当一个沉默基因的复制品取代交配型位点处的常驻信息并因此被表达时，就会发生转换。这些模型预测，沉默（“存储”）位点的突变会在转换过程之后产生有缺陷的MAT位点。因此，研究了HMα突变体在交配型相互转换过程中的行为。结果表明，通过在HMα突变体中转换MATα位点会产生有缺陷的MATa等位基因。因此，来自HMα的遗传信息被转移到交配型位点。这些结果提供了支持这些模型的遗传学证据。
