Rulifson E J, Wu C H, Nusse R
Howard Hughes Medical Institute and Department of Developmental Biology, Stanford University, California 94305, USA.
Mol Cell. 2000 Jul;6(1):117-26.
The Frizzled (Fz) protein in Drosophila is a bifunctional receptor that acts through a GTPase pathway in planar polarity signaling and as a receptor for Wingless (Wg) using the canonical Wnt pathway. We found that the ligand-binding domain (CRD) of Fz has an approximately 10-fold lower affinity for Wg than the CRD of DFz2, a Wg receptor without polarity activity. When the Fz CRD is replaced by the high-affinity CRD of DFz2, the resulting chimeric protein gains Wg signaling activity, yet also retains polarity signaling activity. In contrast, the reciprocal exchange of the Fz CRD onto DFz2 is not sufficient to confer polarity activity to DFz2. This suggests that Fz has an intrinsic capacity for polarity signaling and that high-affinity interaction with Wg couples it to the Wnt pathway.
果蝇中的卷曲蛋白（Fz）是一种双功能受体，它在平面极性信号传导中通过GTPase途径发挥作用，并利用经典的Wnt途径作为无翅蛋白（Wg）的受体。我们发现，Fz的配体结合结构域（CRD）对Wg的亲和力比DFz2（一种无极性活性的Wg受体）的CRD低约10倍。当Fz的CRD被DFz2的高亲和力CRD取代时，产生的嵌合蛋白获得了Wg信号活性，但也保留了极性信号活性。相反，将Fz的CRD与DFz2相互交换不足以赋予DFz2极性活性。这表明Fz具有极性信号传导的内在能力，并且与Wg的高亲和力相互作用将其与Wnt途径耦合。
