Polarized apical sorting of guanylyl cyclase C is specified by a cytosolic signal
Polarized apical sorting of guanylyl cyclase C is specified by a cytosolic signal
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DOI：
10.1111/j.1600-0854.2006.00398.x
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发表时间：
2006-04-01
期刊：
影响因子：
4.5
通讯作者：
Milgram, SL
中科院分区：
文献类型：
--
作者：
Hodson, CA;Ambrogi, IG;Milgram, SL
受体鸟苷酸环化酶通过增加细胞内cGMP来响应配体刺激，从而启动多种细胞信号传导途径。此外，这些蛋白质差异定位于上皮细胞的顶膜和基底外侧膜。我们已经确定了一个区域的11个氨基酸的鸟苷酸环化酶C（GCC）的细胞质COOH末端需要正常的顶端定位在Madin-Darby犬肾（MDCK）细胞。这些氨基酸与先前鉴定的胞质顶端分选决定簇没有显著的序列同源性。然而，这些氨基酸是高度保守的，并且足以赋予白细胞介素-2受体α链（Tac）顶端极性。此外，我们在由过表达GCC的MDCK细胞制备的裂解物中发现了两种分子量的GCC，但仅观察到细胞表面上的完全成熟的种类。在极化的MDCK细胞中使用脉冲追踪分析，我们随着时间的推移跟踪这种成熟物种的产生，发现它仅在顶端细胞表面可检测到。这些数据支持的假设，选择性顶端分选可以确定使用短，胞质氨基酸基序，并认为顶端分选机械的存在可与机器确定为基底外侧蛋白质交通。
Receptor guanylyl cyclases respond to ligand stimulation by increasing intracellular cGMP, thereby initiating a variety of cell-signaling pathways. Furthermore, these proteins are differentially localized at the apical and basolateral membranes of epithelial cells. We have identified a region of 11 amino acids in the cytosolic COOH terminus of guanylyl cyclase C (GCC) required for normal apical localization in Madin-Darby canine kidney (MDCK) cells. These amino acids share no significant sequence homology with previously identified cytosolic apical sorting determinants. However, these amino acids are highly conserved and are sufficient to confer apical polarity to the interleukin-2 receptor alpha-chain (Tac). Additionally, we find two molecular weight species of GCC in lysates prepared from MDCK cells over-expressing GCC but observe only the fully mature species on the cell surface. Using pulse-chase analysis in polarized MDCK cells, we followed the generation of this mature species over time finding it to be detectable only at the apical cell surface. These data support the hypothesis that selective apical sorting can be determined using short, cytosolic amino acid motifs and argue for the existence of apical sorting machinery comparable with the machinery identified for basolateral protein traffic.