A transmembrane segment determines the steady-state localization of an ion-transporting adenosine triphosphatase.
A transmembrane segment determines the steady-state localization of an ion-transporting adenosine triphosphatase.
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跨膜段确定了离子传输腺苷三磷酸酶的稳态定位。
DOI：
10.1083/jcb.148.4.769
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发表时间：
2000-02-21
影响因子：
7.8
通讯作者：
Caplan, M J
中科院分区：
文献类型：
--
作者：
Dunbar, L A;Aronson, P;Caplan, M J
胃壁细胞的H，K-腺苷三磷酸酶（ATP酶）靶向一个受调节的膜室，该膜室响应促分泌素刺激而与顶端质膜融合。先前的工作已经证明，H，K-ATP酶的α亚基编码负责该泵的顶端分布的定位信息，而β亚基携带负责通过将泵从表面取回到调节的细胞内室来停止酸分泌的信号。通过分析由H，K-ATP酶α亚基和高度同源的Na，K-ATP酶α亚基的互补部分组成的许多嵌合泵的分选行为，我们已经鉴定了胃H，K-ATP酶的一部分，其足以将正常基底外侧的Na，K-ATP酶重定向到转染的上皮细胞的顶端表面。该基序位于H，K-ATP酶α亚基的10个预测跨膜结构域中的第4个。虽然已经提出与富含鞘糖脂的膜结构域的相互作用在靶向几种顶端膜蛋白中发挥重要作用，但在洗涤剂不溶性复合物中未发现位于顶端的嵌合体，所述复合物通常富含鞘糖脂。此外，当其两个侧翼序列均衍生自H，K-ATP酶序列时，掺入Na，K-ATP酶α亚基第四跨膜结构域的嵌合体被顶部靶向。这些结果提供了一个定义的顶端定位信号在多位膜转运蛋白的鉴定，并表明，该信号的功能，通过构象之间的相互作用的第四跨膜跨段及其周围的序列结构域。
The H,K-adenosine triphosphatase (ATPase) of gastric parietal cells is targeted to a regulated membrane compartment that fuses with the apical plasma membrane in response to secretagogue stimulation. Previous work has demonstrated that the α subunit of the H,K-ATPase encodes localization information responsible for this pump's apical distribution, whereas the β subunit carries the signal responsible for the cessation of acid secretion through the retrieval of the pump from the surface to the regulated intracellular compartment. By analyzing the sorting behaviors of a number of chimeric pumps composed of complementary portions of the H,K-ATPase α subunit and the highly homologous Na,K-ATPase α subunit, we have identified a portion of the gastric H,K-ATPase, which is sufficient to redirect the normally basolateral Na,K-ATPase to the apical surface in transfected epithelial cells. This motif resides within the fourth of the H,K-ATPase α subunit's ten predicted transmembrane domains. Although interactions with glycosphingolipid-rich membrane domains have been proposed to play an important role in the targeting of several apical membrane proteins, the apically located chimeras are not found in detergent-insoluble complexes, which are typically enriched in glycosphingolipids. Furthermore, a chimera incorporating the Na,K-ATPase α subunit fourth transmembrane domain is apically targeted when both of its flanking sequences derive from H,K-ATPase sequence. These results provide the identification of a defined apical localization signal in a polytopic membrane transport protein, and suggest that this signal functions through conformational interactions between the fourth transmembrane spanning segment and its surrounding sequence domains.