Schüller H J, Entian K D
Medizinisch-Naturwissenschaftliches Forschungszentrum, Universität Tübingen, F.R.G.
Gene. 1988 Jul 30;67(2):247-57. doi: 10.1016/0378-1119(88)90401-5.
The yeast regulatory gene CAT3 has an essential function for the depression of several glucose-repressible enzymes. Therefore, cat3 mutants are unable to grow on maltose or on non-fermentable carbon sources. Unlike the point mutants isolated previously, cat3 null allele strains also failed to utilize raffinose or galactose as sole carbon sources. Sequencing of an 1.6-kb HindIII-BglII fragment complementing cat3 mutations revealed an open reading frame of 322 codons, size of which is in good agreement with the 1.3-kb size of mRNA. No significant similarities with previously sequenced genes could be detected. CAT3-lacZ fusions confirmed the proposed reading frame. A CAT3-lacZ fusion encoding 307 amino acids of CAT3 was able to complement the growth defects of cat3 point mutants and null allele strains. Assay of beta-galactosidase activity under different growth conditions indicated a constitutive expression of the CAT3 gene product. Cellular fractionation studies showed the nuclear localization of the CAT3 protein.
酵母调节基因CAT3对几种葡萄糖阻遏酶的抑制具有重要作用。因此，cat3突变体无法在麦芽糖或非发酵性碳源上生长。与先前分离的点突变体不同，cat3无效等位基因菌株也无法利用棉子糖或半乳糖作为唯一碳源。对一个能互补cat3突变的1.6kb HindIII - BglII片段进行测序，发现了一个由322个密码子组成的开放阅读框，其大小与1.3kb的mRNA大小高度吻合。未检测到与先前测序基因有明显相似性。CAT3 - lacZ融合证实了所提出的阅读框。一个编码CAT3 307个氨基酸的CAT3 - lacZ融合体能够互补cat3点突变体和无效等位基因菌株的生长缺陷。在不同生长条件下对β - 半乳糖苷酶活性的检测表明CAT3基因产物的组成型表达。细胞分级分离研究表明CAT3蛋白定位于细胞核。
