Parker S L, Parker M S, Sallee F R, Balasubramaniam A
Department of Pharmacology, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
Regul Pept. 2007 Dec 4;144(1-3):72-81. doi: 10.1016/j.regpep.2007.06.004. Epub 2007 Jun 21.
Human neuropeptide Y Y2 receptors expressed in CHO cells are largely oligomeric, and upon solubilization are recovered by density gradient centrifugation as approximately 180 kDa complexes of receptor dimers and G-protein heterotrimers. A large fraction of the receptors is inactivated in the presence of pertussis toxin, in parallel with inactivation of Gi alpha subunits (with half-periods of about 4 h for both). This is accompanied by a very long-lasting loss of receptor dimers and of masked surface Y2 sites (an apparent receptor reserve pre-coupled mainly to Gi alpha subunit-containing G-proteins). However, surface Y2 receptors accessible to large peptide agonists are much less sensitive to the toxin. All surface Y2 receptors are rapidly blocked by Y2 antagonist BIIE0246, with a significant loss of the dimers, but with little change of basal Gi activity. However, both dimers and Y2 receptor compartmentalization are restored within 24 h after removal of the antagonist. In CHO cells, the maintenance and organization of Y2 receptors appear to critically depend on functional pertussis toxin-sensitive G-proteins.
在CHO细胞中表达的人神经肽Y Y2受体大多为寡聚体,溶解后通过密度梯度离心回收,为受体二聚体和G蛋白异源三聚体组成的约180 kDa复合物。在百日咳毒素存在的情况下,很大一部分受体失活,同时Giα亚基也失活(两者的半衰期约为4小时)。这伴随着受体二聚体和隐蔽表面Y2位点(一种明显的受体储备,主要与含Giα亚基的G蛋白预偶联)的非常持久的丧失。然而,对大肽激动剂可及的表面Y2受体对毒素的敏感性要低得多。所有表面Y2受体都被Y2拮抗剂BIIE0246迅速阻断,二聚体显著减少,但基础Gi活性变化不大。然而,去除拮抗剂后24小时内,二聚体和Y2受体的区室化都得以恢复。在CHO细胞中,Y2受体的维持和组织似乎严重依赖于功能性百日咳毒素敏感的G蛋白。