Ligand-Directed Chemical Labeling for Visualizing and Analyzing AMPA Receptors in Neurons

Glutamate receptors have essential roles in brain functions, such as memory, learning, and cognition. Recent studies have revealed that strict regulation of AMPA-type glutamate receptor (AMPAR) trafficking is essential for synaptic plasticity, which is a putative cellular mechanism for memory. Conventional biochemical and molecular biological approaches have been widely used for analyzing the trafficking of AMPARs. However, it is still challenging to analyze AMPARs endogenously expressed in neurons. We have developed a new method for the chemical labeling of AMPARs in live cells. This method is based on affinity-based protein labeling using small molecule reagents, termed ligand-directed acyl imidazole (LDAI) chemistry, which allows visualizing AMPARs endogenously expressed in neurons. Recently, we have reported a ligand-directed two-step labeling method, in which LDAI chemistry is combined with bioorthogonal click chemistry. This modified method is suitable for quantifying the localization and trafficking of AMPARs. This chapter provides the experimental and technical details for visualizing and analyzing AMPARs using these chemical-labeling methods in cultured neurons.