Szczypka M S, Wemmie J A, Moye-Rowley W S, Thiele D J
Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor 48109-0606.
J Biol Chem. 1994 Sep 9;269(36):22853-7.
Members of the ATP binding cassette (ABC) protein superfamily transport a variety of substances across biological membranes, including drugs, ions, and peptides. The yeast cadmium factor (YCF1) gene from Saccharomyces cerevisiae is required for cadmium resistance and encodes a 1,515 amino acid protein with extensive homology to both the human multidrug resistance-associated protein (MRP1) and the cystic fibrosis transmembrane conductance regulator (hCFTR). S. cerevisiae cells harboring a deletion of the YCF1 gene are hypersensitive to cadmium compared with wild type cells. Mutagenesis experiments demonstrate that conserved amino acid residues, functionally critical in hCFTR, play a vital role in YCF1-mediated cadmium resistance. Mutagenesis of phenylalanine 713 in the YCF1 nucleotide binding fold 1, which correlates with the delta F508 mutation found in the most common form of cystic fibrosis, completely abolished YCF1 function in cadmium detoxification. Furthermore, substitution of a serine to alanine residue in a potential protein kinase A phosphorylation site in a central region of YCF1, which displays sequence similarity to the central regulatory domain of hCFTR, also rendered YCF1 nonfunctional. These results suggest that YCF1 is composed of modular domains found in human proteins which function in drug and ion transport.
ATP结合盒（ABC）蛋白超家族的成员可将多种物质转运穿过生物膜，包括药物、离子和肽。酿酒酵母的酵母镉因子（YCF1）基因是镉抗性所必需的，它编码一种由1515个氨基酸组成的蛋白质，与人类多药耐药相关蛋白（MRP1）和囊性纤维化跨膜电导调节因子（hCFTR）都具有广泛的同源性。与野生型细胞相比，携带YCF1基因缺失的酿酒酵母细胞对镉高度敏感。诱变实验表明，在hCFTR中功能关键的保守氨基酸残基在YCF1介导的镉抗性中起重要作用。YCF1核苷酸结合结构域1中的苯丙氨酸713发生诱变，这与最常见形式的囊性纤维化中发现的ΔF508突变相关，完全消除了YCF1在镉解毒中的功能。此外，在YCF1中心区域一个潜在的蛋白激酶A磷酸化位点将丝氨酸替换为丙氨酸残基，该区域与hCFTR的中心调节结构域具有序列相似性，这也使YCF1失去功能。这些结果表明，YCF1由人类蛋白质中发现的模块化结构域组成，这些结构域在药物和离子转运中发挥作用。
