Reddy P S, Corley R B
Department of Microbiology, Boston University School of Medicine, MA 02118, USA.
Bioessays. 1998 Jul;20(7):546-54. doi: 10.1002/(SICI)1521-1878(199807)20:7<546::AID-BIES5>3.0.CO;2-I.
The endoplasmic reticulum (ER) uses various mechanisms to ensure that only properly folded proteins enter the secretory pathway. For proteins that oligomerize in the ER, the proper tertiary and quaternary structures must be achieved before their release. Although some proteins fold before oligomerization, others initiate oligomerization cotranslationally. Here, we discuss these different strategies and some of the unique problems they present for the ER quality control system. One mechanism used by the ER is thiol retention. Thiol retention operates by monitoring the redox state of specific cysteine residue(s) and was discovered in studies on the assembly of IgM, a complex oligomeric glycoprotein. This system is also involved in retaining other unassembled proteins in the ER. Mutations that result in uneven numbers of cysteine residues can subject yet other proteins to thiol retention, altering their oligomerization status and function. The implications of these results on the effects of thiol retention on protein function and cell fate are discussed.
内质网（ER）利用多种机制确保只有正确折叠的蛋白质进入分泌途径。对于在内质网中寡聚化的蛋白质，必须先形成正确的三级和四级结构才能释放。虽然一些蛋白质在寡聚化之前就已折叠，但其他蛋白质则在共翻译过程中开始寡聚化。在这里，我们讨论这些不同的策略以及它们给内质网质量控制系统带来的一些独特问题。内质网使用的一种机制是硫醇保留。硫醇保留通过监测特定半胱氨酸残基的氧化还原状态来运作，这是在对复杂寡聚糖蛋白IgM组装的研究中发现的。该系统还参与在内质网中保留其他未组装的蛋白质。导致半胱氨酸残基数量不均的突变会使其他蛋白质受到硫醇保留的影响，改变它们的寡聚化状态和功能。讨论了这些结果对硫醇保留对蛋白质功能和细胞命运影响的意义。
