The cargo receptor p24A facilitates calcium sensing receptor maturation and stabilization in the early secretory pathway.
The cargo receptor p24A facilitates calcium sensing receptor maturation and stabilization in the early secretory pathway.
复制标题
货物受体 p24A 促进早期分泌途径中钙敏感受体的成熟和稳定。
DOI：
10.1016/j.bbrc.2010.03.156
复制
发表时间：
2010
影响因子：
3.1
通讯作者：
Breitwieser,GerdaE
中科院分区：
文献类型：
--
作者：
Stepanchick,Ann;Breitwieser,GerdaE
钙敏感受体（CaSR）是一种家族3/C G蛋白偶联受体，在天然和异源细胞中都具有缓慢和部分靶向质膜的作用。我们确定货物受体家族成员p24 A在酵母双杂交筛选与CaSR羧基末端。在瞬时转染的HEK 293细胞中通过p24 A或CaSR的免疫沉淀证实相互作用。只有无糖基化形式的CaSR与p24 A相互作用。解离可能发生在内质网-高尔基体中间室（ERGIC）或顺式高尔基体中，因为只有对反式高尔基体酶弗林蛋白酶敏感的CaSR突变体的未切割形式与p24 A共免疫沉淀。p24 A和p24 A（ΔGOLD）显著增加总CaSR蛋白和质膜CaSR蛋白，而p24 A（FF/AA）无此作用。T868远端的CaSR羧基末端是对p24 A及其突变体的差异敏感性所必需的。因此，与p24 A的相互作用增加了ER中的CaSR稳定性并增强了质膜靶向。野生型Sar 1 p或T39 N突变体都不增加CaSR成熟或丰度，而H79 G突变体增加了丰度，但阻止了CaSR的成熟。这些结果表明，p24 A是在早期分泌途径中的CaSR运输的限制因素，并且ER和ERGIC之间的循环保护CaSR免于降解。
The calcium sensing receptor (CaSR) is a Family 3/C G protein-coupled receptor with slow and partial targeting to the plasma membrane in both native and heterologous cells. We identified cargo receptor family member p24A in yeast two-hybrid screens with the CaSR carboxyl terminus. Interactions were confirmed by immunoprecipitation of either p24A or CaSR in transiently transfected HEK293 cells. Only the immaturely glycosylated form of CaSR interacts with p24A. Dissociation likely occurs in the endoplasmic reticulum–Golgi intermediate compartment (ERGIC) or cis-Golgi, since only the uncleaved form of a CaSR mutant sensitive to the trans-Golgi enzyme furin was co-immunoprecipitated with p24A. p24A and p24A(ΔGOLD) significantly increased total and plasma membrane CaSR protein but p24A(FF/AA) did not. The CaSR carboxyl terminus distal to T868 is required for differential sensitivity to p24A and its mutants. Interaction with p24A therefore increases CaSR stability in the ER and enhances plasma membrane targeting. Neither wt Sar1p or the T39N mutant increased CaSR maturation or abundance while the H79G mutant increased abundance but prevented maturation of CaSR. These results suggest that p24A is the limiting factor in CaSR trafficking in the early secretory pathway, and that cycling between the ER and ERGIC protects CaSR from degradation.