Transport activity-dependent intracellular sorting of the yeast general amino acid permease.
Transport activity-dependent intracellular sorting of the yeast general amino acid permease.
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DOI：
10.1091/mbc.e10-10-0800
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发表时间：
2011-06-01
影响因子：
3.3
通讯作者：
Kaiser CA
中科院分区：
文献类型：
--
作者：
Cain NE;Kaiser CA
一般氨基酸通透酶Gap1p的细胞内运输受氨基酸丰度的调节。通过使用突变体，改变了一套可以通过Gap1p运输的氨基酸，我们表明，只有那些可以通过Gap1p运输的氨基酸可以作为一个信号，影响Gap1p分选。酿酒酵母（Saccharomycescerevisiae）的一般氨基酸通透酶Gap1p的胞内运输受氨基酸丰度的调节。当氨基酸缺乏时，Gap1p被分选到质膜上，而当氨基酸丰富时，Gap1p从高尔基体通过多泡内体（MVE）被分选到液泡中。在这里，我们测试的假设，即Gap1p本身是传感器的氨基酸丰度通过检查Gap1p突变体改变底物特异性和运输活性的贩运。我们发现，贩运的突变体Gap1pA297V，这不运输碱性氨基酸，也不受这些氨基酸。此外，我们已经确定了一个催化失活的突变体，不响应复杂的氨基酸混合物和组成型排序Gap1p的质膜。以前，我们表明，氨基酸管理的倾向Gap1p从MVE再循环到质膜。在这里，我们建议，在基板的存在下，Gap1p的稳态构象转移到一个状态，是无法从MVE回收。这些结果表明，一个吝啬的监管机制，Gap1p的感觉其运输基板设置在细胞表面的转运活性的适当水平。
Intracellular trafficking of the general amino acid permease, Gap1p, is regulated by amino acid abundance. Through the use of mutants that alter the set of amino acids that can be transported by Gap1p, we show that only those amino acids that can be transported by Gap1p can act as a signal to affect Gap1p sorting. Intracellular trafficking of the general amino acid permease, Gap1p, of Saccharomyces cerevisiae is regulated by amino acid abundance. When amino acids are scarce Gap1p is sorted to the plasma membrane, whereas when amino acids are abundant Gap1p is sorted from the trans-Golgi through the multivesicular endosome (MVE) and to the vacuole. Here we test the hypothesis that Gap1p itself is the sensor of amino acid abundance by examining the trafficking of Gap1p mutants with altered substrate specificity and transport activity. We show that trafficking of mutant Gap1pA297V, which does not transport basic amino acids, is also not regulated by these amino acids. Furthermore, we have identified a catalytically inactive mutant that does not respond to complex amino acid mixtures and constitutively sorts Gap1p to the plasma membrane. Previously we showed that amino acids govern the propensity of Gap1p to recycle from the MVE to the plasma membrane. Here we propose that in the presence of substrate the steady-state conformation of Gap1p shifts to a state that is unable to be recycled from the MVE. These results indicate a parsimonious regulatory mechanism by which Gap1p senses its transport substrates to set an appropriate level of transporter activity at the cell surface.