How G protein-coupled receptors (GPCRs) are organized at the cell surface remains highly contentious. Single-molecule (SM) imaging is starting to inform this debate as receptor behavior can now be visualized directly, without the need for interpreting ensemble data. The limited number of SM studies of GPCRs undertaken to date have strongly suggested that dimerization is at most transient, and that most receptors are monomeric at any given time. However, even SM data has its caveats and needs to be interpreted carefully. Here, we discuss the types of SM imaging strategies used to examine GPCR stoichiometry and consider some of these caveats. We also emphasize that attempts to resolve the debate ought to rely on orthogonal approaches to measuring receptor stoichiometry.

G 蛋白偶联受体 (GPCR) 在细胞表面的组织方式仍然存在很大争议。单分子 (SM) 成像开始为这场辩论提供信息，因为受体行为现在可以直接可视化，而无需解释整体数据。迄今为止对 GPCR 进行的有限数量的 SM 研究强烈表明二聚化至多是短暂的，并且大多数受体在任何给定时间都是单体的。然而，即使是 SM 数据也有其警告，需要仔细解读。在这里，我们讨论了用于检查 GPCR 化学计量的 SM 成像策略的类型，并考虑了其中的一些注意事项。我们还强调，解决争论的尝试应该依靠正交方法来测量受体化学计量。