Redd Kacy J, Oberdick John, McCoy John, Denker Bradley M, Luo Yuan
Department of Biological Sciences, University of Southern Mississippi, 2609 W. 4th Street, Hattiesburg, MS 39406-5018, USA.
J Neurosci Res. 2002 Dec 1;70(5):631-7. doi: 10.1002/jnr.10460.
Previously, we have demonstrated a novel interaction between Galpha(o) protein and Purkinje cell protein-2 (Pcp2, also known as L7) in vitro and in transfected cells (Luo and Denker [1999] J. Biol. Chem. 274:10685-10688). Pcp2 is uniquely expressed in cerebellar Purkinje cells and in retinal bipolar neurons, and it may function as a cell-type specific modulator for G protein-mediated cell signaling. This interaction has been further evaluated in the present studies. Coimmunoprecipitation experiments reveal that Pcp2 associates with Galpha(o) in vivo in mouse cerebellum and eye extract. Pcp2 also associate with Galpha(i2) in the cerebellum. No detectable associations of Pcp2 with Galpha(z) and Galpha(q) subunits are observed. The association of Galpha(o) and Pcp2 is detected at postnatal day 1 (P1), and the association remains stable from day 3 (P3) until adulthood. Further, immunofluorescent double labeling and confocal microscopy suggest that Pcp2 and Galpha(o) are colocalized in the distal processes of cerebellar Purkinje cells including axonal endings and dendritic spines. Taken together, these findings indicate colocalization and association of Galpha(o) and Pcp2 in cerebellum and suggest a functional role in regions of synaptic activity.
此前，我们已在体外及转染细胞中证实了Gα(o)蛋白与浦肯野细胞蛋白2（Pcp2，也称为L7）之间存在新型相互作用（Luo和Denker [1999]《生物化学杂志》274:10685 - 10688）。Pcp2在小脑浦肯野细胞和视网膜双极神经元中特异性表达，它可能作为G蛋白介导的细胞信号传导的细胞类型特异性调节剂发挥作用。在本研究中对这种相互作用进行了进一步评估。免疫共沉淀实验表明，在小鼠小脑和眼提取物中，Pcp2在体内与Gα(o)相关联。在小脑中，Pcp2还与Gα(i2)相关联。未观察到Pcp2与Gα(z)和Gα(q)亚基有可检测到的关联。在出生后第1天（P1）检测到Gα(o)与Pcp2的关联，并且从第3天（P3）到成年期这种关联一直保持稳定。此外，免疫荧光双标记和共聚焦显微镜检查表明，Pcp2和Gα(o)在小脑浦肯野细胞的远端突起中共同定位，包括轴突末梢和树突棘。综上所述，这些发现表明Gα(o)和Pcp2在小脑中共同定位并相互关联，提示它们在突触活动区域发挥功能作用。
