Spatial intensity distribution analysis (SpIDA) is a recently developed approach for determining quaternary structure information on fluorophore-labelled proteins of interest in situ. It can be applied to live or fixed cells and native tissue. Using confocal images, SpIDA generates fluorescence intensity histograms that are analysed by super-Poissonian distribution functions to obtain density and quantal brightness values of the fluorophore-labelled protein of interest. This allows both expression level and oligomerisation state of the protein to be determined. We describe the application of SpIDA to investigate the oligomeric state of G protein-coupled receptors (GPCRs) at steady state and following cellular challenge, and consider how SpIDA may be used to explore GPCR quaternary organisation in pathophysiology and to stratify medicines.

空间强度分布分析 (SpIDA) 是最近开发的一种方法，用于原位确定荧光团标记的感兴趣蛋白质的四级结构信息. 它可以应用于活细胞或固定细胞和天然组织。SpIDA 使用共聚焦图像生成荧光强度直方图，通过超泊松分布函数进行分析，以获得荧光团标记的感兴趣蛋白质的密度和量子亮度值。这允许确定蛋白质的表达水平和寡聚状态。我们描述了 SpIDA 在研究稳态和细胞攻击后 G 蛋白偶联受体 (GPCR) 的寡聚状态中的应用，并考虑如何使用 SpIDA 探索病理生理学中的 GPCR 四元组织和药物分层。