Conformational maturation and post-ER multisubunit assembly of gap junction proteins.
Conformational maturation and post-ER multisubunit assembly of gap junction proteins.
复制标题
间隙连接蛋白的构象成熟和内质网后多亚基组装。
DOI：
10.1091/mbc.e09-01-0062
复制
发表时间：
2009
影响因子：
3.3
通讯作者：
Musil,LindaS
中科院分区：
文献类型：
--
作者：
Vanslyke,JudyK;Naus,ChristianC;Musil,LindaS
For all previously well-characterized oligomeric integral membrane proteins, folding, multisubunit assembly, and recognition of conformationally immature molecules for degradation occurs at their organelle of synthesis. This cannot, however, be the case for the gap junction–forming protein connexin43 (Cx43), which when endogenously expressed undergoes multisubunit assembly into connexons only after its transport to thetrans-Golgi network. We have developed two novel assays to assess Cx43 folding and assembly: acquisition of resistance of disulfide bonds to reduction by extracellularly added DTT and Triton X-114 detergent phase partitioning. We show that Cx43 synthesized at physiologically relevant levels undergoes a multistep conformational maturation process in which folding of connexin monomers within the ER is a prerequisite for multisubunit assembly in the TGN. Similar results were obtained with Cx32, disproving the widely reported contention that the site of endogenous β connexin assembly is the ER. Exogenous overexpression of Cx43, Cx32, or Cx26 allows these events to take place within the ER, the first example of the TGN and ER as alternative sites for oligomeric assembly. Our findings also constitute the first biochemical evidence that defective connexin folding is a cause of the human disorder X-linked Charcot-Marie-Tooth disease.
