The tetraspanin CD63 enhances the internalization of the H,K-ATPase β-subunit
The tetraspanin CD63 enhances the internalization of the H,K-ATPase β-subunit
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DOI：
10.1073/pnas.2536699100
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发表时间：
2003-12-23
影响因子：
11.1
通讯作者：
Caplan, MJ
中科院分区：
文献类型：
--
作者：
Duffield, A;Kamsteeg, EJ;Caplan, MJ
四跨膜蛋白CD 63位于晚期内体、溶酶体、分泌囊泡和质膜上，并在这些隔室之间移动。我们发现，CD 63也存在于tubulovesicular元素，细胞内的隔间，包含H，K-ATP酶在未受刺激的胃壁细胞。H，KATP酶β亚基和CD 63共定位于壁细胞中，并形成可共沉淀的复合物。当β亚基和CD 63在COS-7细胞中共表达时，它们也相互作用。此外，与CD 63一起表达诱导β亚基从细胞表面重新分布到CD 63（+）细胞内区室。免疫荧光和生物化学实验表明，这种再分布是通过增强与CD 63复合的H，K-ATP酶β亚基的内吞作用而发生的。β-亚基与突变型CD 63多肽的共表达表明β-亚基的增强的内化依赖于CD 63与衔接蛋白复合物2和3相互作用的能力。这些数据表明，CD 63作为一个衔接蛋白，其相互作用的合作伙伴的细胞内吞机制，并建议一个以前未知的蛋白质运输的作用四跨膜蛋白。
The tetraspanin CD63 resides in late endosomes, lysosomes, secretory vesicles, and at the plasma membrane, and it moves among these compartments. We find that CD63 is present also in tubulovesicular elements, the intracellular compartments that contain the H,K-ATPase in unstimulated gastric parietal cells. The H,KATPase beta-subunit and CD63 colocalize in parietal cells and form a complex that can be coprecipitated. The beta-subunit and CD63 also interact when they are coexpressed in COS-7 cells. Furthermore, expression with CD63 induces the redistribution of the beta-subunit from the cell surface to CD63(+) intracellular compartments. Immunofluorescence and biochemical experiments reveal that this redistribution occurs by enhanced endocytosis of H,K-ATPase beta-subunit complexed with CD63. Coexpression of the beta-subunit with mutant CD63 polypeptides demonstrates that the enhanced internalization of the beta-subunit depends on the capacity of CD63 to interact with adaptor protein complexes 2 and 3. These data indicate that CD63 serves as an adaptor protein that links its interaction partners to the endocytic machinery of the cell and suggest a previously uncharacterized protein-trafficking role for the tetraspanins.