A pathway for targeting soluble misfolded proteins to the yeast vacuole
A pathway for targeting soluble misfolded proteins to the yeast vacuole
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DOI：
10.1083/jcb.135.3.623
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发表时间：
1996-11-01
影响因子：
7.8
通讯作者：
Kaiser, CA
中科院分区：
文献类型：
--
作者：
Hong, E;Davidson, AR;Kaiser, CA
我们通过将λ抑制蛋白的nh2末端结构域的突变形式融合到分泌的蛋白转化酶中，评估了酿酒酵母分泌途径中错误折叠蛋白结构域的命运。携带野生型抑制蛋白结构域的杂交蛋白大多分泌到细胞表面，而导致抑制蛋白结构域热力学不稳定的氨基酸取代的杂交蛋白保留在细胞内。令人惊讶的是，保留的杂交种是在液泡中发现的，液泡蛋白酶降解了液泡中的抑制物。以下观察结果表明，受体介导的高尔基体管腔中突变抑制结构域的识别将这些杂交融合物靶向液泡。(a)转化酶-抑制因子融合物，像野生型转化酶一样，在内质网管腔中表现为可溶性蛋白。(b)靶向液泡是饱和的，因为携带突变抑制因子的杂交体的过表达增加了出现在细胞表面的融合蛋白的比例。(c)最后，VPS10基因编码负责将羧肽酶Y靶向到液泡的跨膜高尔基受体，该基因的缺失导致突变杂交体转移到细胞表面。总之，这些发现表明，酵母通过受体介导的转运到液泡，有一种降解非天然腔内蛋白的补救途径。
We have evaluated the fate of misfolded protein domains in the Saccharomyces cerevisiae secretory pathway by fusing mutant forms of the NH2-terminal domain of lambda repressor protein to the secreted protein invertase, The hybrid protein carrying the wild-type repressor domain is mostly secreted to the cell surface, whereas hybrid proteins with amino acid substitutions that cause the repressor domain to be thermodynamically unstable are retained intracellularly. Surprisingly, the retained hybrids are found in the vacuole, where the repressor moiety is degraded by vacuolar proteases. The following observations indicate that receptor-mediated recognition of the mutant repressor domain in the Golgi lumen targets these hybrid fusions to the vacuole. (a) The invertase-repressor fusions, like wild-type invertase, behave as soluble proteins in the ER lumen. (b) Targeting to the vacuole is saturable since overexpression of the hybrids carrying mutant repressor increases the fraction of fusion protein that appears at the cell surface. (c) Finally, deletion of the VPS10 gene, which encodes the transmembrane Golgi receptor responsible for targeting carboxypeptidase Y to the vacuole, causes the mutant hybrids to be diverted to the cell surface. Together these findings suggest that yeast have a salvage pathway for degradation of nonnative luminal proteins by receptor-mediated transport to the vacuole.