Lawson J E, Douglas M G
Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas 75235.
J Biol Chem. 1988 Oct 15;263(29):14812-8.
Genetic and biochemical analysis of Saccharomyces cerevisiae containing a disruption of the nuclear gene (AAC1) encoding the mitochondrial ADP/ATP carrier has revealed a second gene for this protein. The second gene, designated AAC2, has been isolated by genetic complementation and sequenced. AAC2 contains a 954-base pair open reading frame coding for a protein of 318 amino acids which is highly homologous to the AAC1 gene product except that it is nine amino acids longer at the NH2 terminus. The two yeast genes are highly conserved at the level of DNA and protein and share identity with the ADP/ATP carriers from other organisms. Both genes complement an ADP/ATP carrier defect (op1 or pet9). However, the newly isolated gene AAC2 need be present only in one or two copies while the previously isolated AAC1 gene must be present in multiple copies to support growth dependent on a functional carrier protein. This gene dosage-dependent complementation combined with the high degree of conservation suggest that these two functionally equivalent genes may be differentially expressed.
对含有编码线粒体ADP/ATP载体的核基因（AAC1）缺失的酿酒酵母进行遗传和生化分析，揭示了该蛋白的第二个基因。通过遗传互补分离出了第二个基因，命名为AAC2，并进行了测序。AAC2包含一个954个碱基对的开放阅读框，编码一个318个氨基酸的蛋白质，该蛋白质与AAC1基因产物高度同源，只是在NH2末端长了九个氨基酸。这两个酵母基因在DNA和蛋白质水平上高度保守，并与其他生物的ADP/ATP载体具有同源性。两个基因都能弥补ADP/ATP载体缺陷（op1或pet9）。然而，新分离的基因AAC2只需存在一两个拷贝，而先前分离的AAC1基因必须存在多个拷贝才能支持依赖功能性载体蛋白的生长。这种基因剂量依赖性互补以及高度保守性表明，这两个功能等效的基因可能存在差异表达。
