Chun M, Liyanage U K, Lisanti M P, Lodish H F
Whitehead Institute for Biomedical Research, Cambridge, MA 02142.
Proc Natl Acad Sci U S A. 1994 Nov 22;91(24):11728-32. doi: 10.1073/pnas.91.24.11728.
Caveolae are small invaginations of the plasma membrane 50-100 nm in diameter. Since calcium channels, inositol 1,4,5-trisphosphate receptors, and heterotrimeric GTP-binding proteins (G proteins) are localized in caveolae, they may participate in signal transduction by G protein-coupled receptors. Here we show that the G protein-coupled endothelin receptor subtype A (ETA) and its bound endothelin ligand are found in plasma membrane caveolae. ETA and its bound ligand coimmunoprecipitate with caveolin, a structural component of caveolae, in extracts of cells expressing transfected ETA receptors. Confocal fluorescence microscopy shows colocalization of ETA receptors and caveolin in micropatches at or near the plasma membrane, in the absence of endothelin ligands. These observations demonstrate a functional role for plasma membrane caveolae in signal transduction by this G protein-coupled receptor.
小窝是质膜上直径为50 - 100纳米的小凹陷。由于钙通道、肌醇1,4,5 -三磷酸受体和异源三聚体GTP结合蛋白（G蛋白）定位于小窝中，它们可能参与G蛋白偶联受体的信号转导。在此我们表明，G蛋白偶联的内皮素A受体亚型（ETA）及其结合的内皮素配体存在于质膜小窝中。在表达转染ETA受体的细胞提取物中，ETA及其结合的配体与小窝的结构成分小窝蛋白共免疫沉淀。共聚焦荧光显微镜显示，在没有内皮素配体的情况下，ETA受体和小窝蛋白在质膜处或附近的微小区域共定位。这些观察结果证明了质膜小窝在这种G蛋白偶联受体的信号转导中具有功能性作用。
