G-protein-coupled receptors function as oligomers in vivo
G-protein-coupled receptors function as oligomers in vivo
复制标题
DOI：
10.1016/s0960-9822(00)00386-9
复制
发表时间：
2000-03-23
期刊：
影响因子：
9.2
通讯作者：
Blumer, KJ
中科院分区：
文献类型：
--
作者：
Overton, MC;Blumer, KJ
激素、感觉刺激、神经递质和趋化因子通过激活G蛋白偶联受体（GPCR）发出信号[1]。尽管GPCR被认为是单体，但它们可以形成SDS抗性二聚体，并且两个非功能性或相关GPCR的共表达可以导致活性的拯救或功能的修饰[2-10]。此外，对应于GPCR的第三胞质环的肽的二聚化增加了它们作为体外G蛋白激活剂的效力[11]，并且二聚化的肽抑制剂减少β（2）-肾上腺素能受体信号传导[3]。然而，目前尚不清楚GPCR是否作为单体或寡聚体存在于完整的细胞和膜中，激动剂结合是否调节单体-寡聚体平衡，或者寡聚化是否支配GPCR功能。在这里，我们报告说，α-因子受体，GPCR的STE 2基因在酵母酿酒酵母的产品，是寡聚体在完整的细胞和膜。与青色或黄色荧光蛋白（CFP或YFP）标记的受体的共表达导致有效的荧光共振能量转移（FRET）由于稳定的协会，而不是碰撞相互作用。单体-寡聚体平衡不受激动剂、拮抗剂或G蛋白异源三聚体结合的影响。寡聚化进一步证明了拯救内吞缺陷受体与共表达的野生型受体。显性干扰受体突变体通过与野生型受体相互作用而不是通过隔离G蛋白异源三聚体来抑制信号传导。我们认为，寡聚化是可能支配GPCR信号和调节。
Hormones, sensory stimuli, neurotransmitters and chemokines signal by activating G-protein-coupled receptors (GPCRs) [1]. Although GPCRs are thought to function as monomers, they can form SDS-resistant dimers, and coexpression of two non-functional or related GPCRs can result in rescue of activity or modification of function [2-10]. Furthermore, dimerization of peptides corresponding to the third cytoplasmic loops of GPCRs increases their potency as activators of G proteins in vitro [11], and peptide inhibitors of dimerization diminish beta(2)-adrenergic receptor signaling [3]. Nevertheless, it is not known whether GPCRs exist as monomers or oligomers in intact cells and membranes, whether agonist binding regulates monomer-oligomer equilibrium, or whether oligomerization governs GPCR function. Here, we report that the alpha-factor receptor, a GPCR that is the product of the STE2 gene in the yeast Saccharomyces cerevisiae, is oligomeric in intact cells and membranes. Coexpression of receptors tagged with the cyan or yellow fluorescent proteins (CFP or YFP) resulted in efficient fluorescence resonance energy tra nsf er (FRET) due to stable association rather than collisional interaction. Monomer-oligomer equilibrium was unaffected by binding of agonist, antagonist, or G protein heterotrimers. Oligomerization was further demonstrated by rescuing endocytosis defective receptors with coexpressed wild-type receptors. Dominant-interfering receptor mutants inhibited signaling by interacting with wild-type receptors rather than by sequestering G protein heterotrimers. We suggest that oligomerization is likely to govern GPCR signaling and regulation.