Bird P, Gething M J, Sambrook J
Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas 75235.
J Biol Chem. 1990 May 25;265(15):8420-5.
We have previously shown that the signal sequence of the Saccharomyces cerevisiae vacuolar protein carboxypeptidase Y (CPY) does not function in mammalian cells unless a glycine residue in the central core is replaced by leucine. Additional mutants were constructed to investigate the features of this hydrophobic core (h) region that are important for signal sequence function in mammalian cells. We find that the degree of hydrophobicity of the h region of any particular mutant signal is directly related to the efficiency with which it directs the translocation of CPY. A minimal h region in a functional signal appears to consist of five hydrophobic residues interrupted by 1 glycine. Analysis of potential secondary structures suggests that a functional mutant signal is more likely than the nonfunctional CPY signal to adopt either a beta strand or an alpha-helical conformation.
我们之前已经表明，酿酒酵母液泡蛋白羧肽酶Y（CPY）的信号序列在哺乳动物细胞中不起作用，除非中央核心区的一个甘氨酸残基被亮氨酸取代。构建了其他突变体以研究该疏水核心（h）区域对哺乳动物细胞中信号序列功能重要的特征。我们发现任何特定突变信号的h区域的疏水性程度与其指导CPY转运的效率直接相关。功能性信号中的最小h区域似乎由五个被1个甘氨酸中断的疏水残基组成。对潜在二级结构的分析表明，功能性突变信号比无功能的CPY信号更有可能采用β链或α螺旋构象。
