Russell S J, Sathyanarayana U G, Johnston S A
Department of Internal Medicine, Graduate Program in Biochemistry and Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75235-8573, USA.
J Biol Chem. 1996 Dec 20;271(51):32810-7. doi: 10.1074/jbc.271.51.32810.
Using a genetic strategy designed to find proteins involved in the function of the Saccharomyces cerevisiae transcriptional activator GAL4, we isolated mutants in two genes which rescue a class of gal4 activation domain mutants. One of these genes, SUG1, encodes a member of a large family of putative ATPases, the Conserved ATPase containing Domain (CAD) proteins (also known as AAA proteins) that are involved in a wide variety of cellular functions. Subsequently, SUG1 was identified as a subunit of the 26 S proteasome. We have now cloned the gene defined by the second complementation group. SUG2 encodes an essential 49-kDa protein that is also a member of the CAD family and is 43% identical to SUG1. The mutation in sug2-1, like that in sug1-1, is found in the CAD near the highly conserved ATPase motif. We present biochemical and genetic evidence that SUG2 is associated in vivo with SUG1 and is a novel CAD protein subunit of the 26 S proteasome. With its highly conserved mammalian homologs, human p42 and ground squirrel CADp44, SUG2 defines a new class of proteasomal CAD proteins.
利用一种旨在寻找参与酿酒酵母转录激活因子GAL4功能的蛋白质的遗传策略，我们分离出了两个基因中的突变体，这些突变体可挽救一类gal4激活域突变体。其中一个基因SUG1编码一个庞大的假定ATP酶家族的成员，即含保守ATP酶结构域（CAD）的蛋白质（也称为AAA蛋白），它们参与多种细胞功能。随后，SUG1被鉴定为26S蛋白酶体的一个亚基。我们现已克隆了由第二个互补组定义的基因。SUG2编码一种必需的49 kDa蛋白质，它也是CAD家族的成员，与SUG1有43%的同源性。sug2-1中的突变，与sug1-1中的突变一样，位于高度保守的ATP酶基序附近的CAD中。我们提供了生化和遗传证据，证明SUG2在体内与SUG1相关联，并且是26S蛋白酶体的一种新型CAD蛋白质亚基。与它高度保守的哺乳动物同源物人类p42和地松鼠CADp44一起，SUG2定义了一类新的蛋白酶体CAD蛋白质。
