Goutte C, Johnson A D
Department of Biochemistry and Biophysics, University of California, San Francisco 94143.
Cell. 1988 Mar 25;52(6):875-82. doi: 10.1016/0092-8674(88)90429-1.
The alpha 2 protein of S. cerevisiae, the product of the MAT alpha 2 gene, represses a set of cell-type-specific genes (the a-specific genes) by binding to an operator sequence upstream of each gene. We demonstrate that a second yeast regulatory protein, a1, the product of the MATa1 gene, can alter the binding specificity of alpha 2 so that it no longer recognizes the a-specific gene operator, but instead acquires the ability to recognize a different operator sequence found upstream of haploid-specific genes. Thus, under the influence of a1, alpha 2 can repress haploid-specific genes. An alpha cell expresses alpha 2 but not a1, so that alpha 2 turns off only the a-specific genes. An a/alpha cell makes both a1 and alpha 2, in a ratio that ensures that alpha 2 is distributed between two distinct binding modes: the alpha 2 binding mode and the a1-alpha 2 binding mode. Thus in an a/alpha cell, alpha 2 represses two distinct classes of genes.
酿酒酵母的α2蛋白是MATα2基因的产物，它通过与每个基因上游的操纵序列结合来抑制一组细胞类型特异性基因（a特异性基因）。我们证明，第二种酵母调节蛋白a1是MATa1基因的产物，它可以改变α2的结合特异性，使其不再识别a特异性基因操纵子，而是获得识别单倍体特异性基因上游不同操纵序列的能力。因此，在a1的影响下，α2可以抑制单倍体特异性基因。α细胞表达α2但不表达a1，因此α2仅关闭a特异性基因。a/α细胞同时产生a1和α2，其比例确保α2分布在两种不同的结合模式之间：α2结合模式和a1-α2结合模式。因此，在a/α细胞中，α2抑制两类不同的基因。
