Lipid phosphate phosphatases 1 and 3 are localized in distinct lipid rafts
Lipid phosphate phosphatases 1 and 3 are localized in distinct lipid rafts
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DOI：
10.1093/jb/mvj195
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发表时间：
2006-11-01
影响因子：
2.7
通讯作者：
Kanoh, Hideo
中科院分区：
文献类型：
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作者：
Kai, Masahiro;Sakane, Fumio;Kanoh, Hideo
脂质磷酸磷酸酶（Lipid Phosphate Phosphatases，LPPs）是一种具有六个跨膜结构域的膜蛋白，可使多种细胞外脂质磷酸盐脱磷酸。虽然LPP 3是已知的结合到Triton X-100不溶性筏，我们在这里报告，LPP 1也与脂质筏不同于那些窝藏LPP 3。我们发现，LPP 1是Triton X-100可溶性的，但CHAPS不溶于内源性表达LPP 1的LNCaP细胞和几种LPP 1 eDNA转染的细胞，包括NIH 3 T3成纤维细胞。除了非离子去污剂不溶性之外，LPP 1还具有如下几种用于筏定位蛋白质的性质：第一，CHAPS不溶性对肌动蛋白破坏药物细胞松弛素D具有抗性;第二，CHAPS不溶性LPP 1漂浮在Optiprep密度梯度中;第三，LPP 1的CHAPS不溶性因胆固醇耗尽而丧失;最后，LPP 1的亚细胞分布模式仅与筏标记物霍乱毒素B亚基的亚细胞分布模式重叠。有趣的是，共聚焦显微镜分析表明，LPP 1分布到膜室不同的LPP 3。使用各种LPP 1/LPP 3嵌合体的分析显示，它们的第一胞外区决定不同的Triton X-100溶解度。这些结果表明，LPP 1和LPP 3分布在不同的脂筏，可以提供独特的微环境，定义其非冗余的生理功能。
Lipid phosphate phosphatases (LPPs), integral membrane proteins with six transmembrane domains, dephosphorylate a variety of extracellular lipid phosphates. Although LPP3 is already known to bind to Triton X-100-insoluble rafts, we here report that LPP1 is also associated with lipid rafts distinct from those harboring LPP3. We found that LPP1 was Triton X-100-soluble, but CHAPS-insoluble in LNCaP cells endogenously expressing LPP1 and several LPP1 eDNA-transfected cells including NIH3T3 fibroblasts. In addition to the non-ionic detergent insolubility, LPP1 further possessed several properties formulated for raft-localizing proteins as follows: first, the CHAPS-insolubility was resistant to the actin-disrupting drug cytochalasin D; second, the CHAPS-insoluble LPP1 floated in an Optiprep density gradient; third, the CHAPS insolubility of LPP1 was lost by cholesterol depletion; and finally, the subcellular distribution pattern of LPP1 exclusively overlapped with that of a raft marker, cholera toxin B subunit. Interestingly, confocal microscopic analysis showed that LPP1 was distributed to membrane compartments distinct from those of LPP3. Analysis using various LPP1/LPP3 chimeras revealed that their first extracellular regions determine the different Triton X-100 solubilities. These results indicate that LPP1 and LPP3 are distributed in distinct lipid rafts that may provide unique microenvironments defining their non-redundant physiological functions.