Department of Biochemistry, Faculty of Medicine/Graduate School of Medicine, University of Yamanashi, Chuo, Japan.
J Biochem. 2011 Jun;149(6):693-700. doi: 10.1093/jb/mvr023. Epub 2011 Feb 15.
The planar cell polarity (PCP) protein, Prickle (Pk), is conserved in invertebrates and vertebrates, and regulates cellular morphogenesis and movement. Vertebrate Pk consists of at least two family members, Pk1 and Pk2, both of which are expressed in the brain; however, their localization and function at synapses remain elusive. Here, we show that Pk2 is expressed mainly in the adult brain and is tightly associated with the postsynaptic density (PSD) fraction obtained by subcellular fractionation. In primary cultured rat hippocampal neurons, Pk2 is colocalized with PSD-95 and synaptophysin at synapses. Moreover, immunoelectron microcopy shows that Pk2 is localized at the PSD of asymmetric synapses in the hippocampal CA1 region. Biochemical assays identified that Pk2 forms a complex with PSD proteins including PSD-95 and NMDA receptor subunits via the direct binding to the C-terminal guanylate kinase domain of PSD-95. These results indicate that Pk2 is a novel PSD protein that interacts with PSD-95 and NMDA receptors through complex formations in the brain.
平面细胞极性 (PCP) 蛋白 Prickle (Pk) 在无脊椎动物和脊椎动物中是保守的，调节细胞形态发生和运动。脊椎动物 Pk 至少由两个家族成员 Pk1 和 Pk2 组成，它们都在大脑中表达；然而，它们在突触处的定位和功能仍然难以捉摸。在这里，我们表明 Pk2 主要在成年大脑中表达，并与通过亚细胞分级分离获得的突触后密度 (PSD) 部分紧密相关。在原代培养的大鼠海马神经元中，Pk2 与 PSD-95 和突触小泡蛋白在突触处共定位。此外，免疫电镜显示 Pk2 定位于海马 CA1 区不对称突触的 PSD 上。生化分析表明，Pk2 通过与 PSD-95 的 C 端鸟苷酸激酶结构域直接结合，与 PSD 蛋白包括 PSD-95 和 NMDA 受体亚基形成复合物。这些结果表明 Pk2 是一种新型的 PSD 蛋白，通过在大脑中的复合物形成与 PSD-95 和 NMDA 受体相互作用。
