Growth hormone receptor targeting to lipid rafts requires extracellular subdomain 2.
Growth hormone receptor targeting to lipid rafts requires extracellular subdomain 2.
复制标题
靶向脂筏的生长激素受体需要细胞外子结构域 2。
DOI：
10.1016/j.bbrc.2009.11.072
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发表时间：
2010
影响因子：
3.1
通讯作者：
Frank,StuartJ
中科院分区：
文献类型：
--
作者：
Yang,Ning;Jiang,Jing;Deng,Luqin;Waters,MichaelJ;Wang,Xiangdong;Frank,StuartJ
生长激素受体（GHR）是一种单一的跨膜糖蛋白二聚体，在其细胞外结构域（ECD）结合生长激素。GH激活GHR胞内结构域（ICD）相关酪氨酸激酶JAK2，导致细胞内信号传导。我们之前发现，质膜（PM）相关的GHR在膜的脂质筏（LR）成分中显著富集，并且GHR在质膜区域的定位可能通过影响途径激活的特征来调节GH信号。在这项研究中，我们使用缺乏内源性JAK2和GHR的重组系统检测了GHR的LR定位的决定因素。通过非洗涤剂提取和多步分离，我们发现GHR在独立于JAK2表达的LR部分高度富集。在含有JAK2的转染物中检测了各种GHR突变体。在原生跨膜结构域（TMD）被不相关的LDL受体取代的GHR和缺乏ICD的GHR中，观察到LR浓度。因此，LR协会既不需要TMD，也不需要ICD。同样，缺乏ECD的GHR，除了膜-近端ECD干区，只有最低限度的lr集中。在全长受体的背景下，具有内部茎缺失的突变体与野生型相似，是lr集中的。缺乏ECD子结构域1的GHR到达PM，呈低浓度集中；缺乏ECD子结构域2的GHR也到达PM，但不呈低浓度集中。这些数据表明，LR靶向位于ECD亚结构域2，这是一个相对不参与GH结合的区域。
GH receptor (GHR) is a single membrane-spanning glycoprotein dimer that binds GH in its extracellular domain (ECD). GH activates the GHR intracellular domain (ICD)-associated tyrosine kinase, JAK2, which causes intracellular signaling. We previously found that plasma membrane (PM)-associated GHR was dramatically enriched in the lipid raft (LR) component of the membrane and that localization of GHR within PM regions may regulate GH signaling by influencing the profile of pathway activation. In this study, we examined determinants of LR localization of the GHR using a reconstitution system which lacks endogenous JAK2 and GHR. By non-detergent extraction and multistep fractionation, we found that GHR was highly enriched in the LR fraction independent of JAK2 expression. Various GHR mutants were examined in transfectants harboring JAK2. LR concentration was observed for a GHR in which the native transmembrane domain (TMD) is replaced by that of the unrelated LDL receptor and for a GHR that lacks its ICD. Thus, LR association requires neither the TMD nor the ICD. Similarly, a GHR that lacks the ECD, except for the membrane-proximal ECD stem region, was only minimally LR-concentrated. Mutants with internal stem deletions in the context of the full-length receptor were LR-concentrated similar to the wild-type. A GHR lacking ECD subdomain 1 reached the PM and was LR-concentrated, while one lacking ECD subdomain 2, also reached the PM, but was not LR-concentrated. These data suggest LR targeting resides in ECD subdomain 2, a region relatively uninvolved in GH binding.