Proteomic Analysis of an Interactome for Long-Form AMPA Receptor Subunits

Glutamate receptors of the AMPA-type mediate fast excitatory synaptic transmission in the central nervous system and play key roles in synaptic plasticity. The binding of these receptors to a variety of proteins is known to regulate their targeting to the synapse and consequently to modulate synaptic strength, as well as to modify receptor characteristics. In this study, a proteomic screening was conducted in order to identify new binding partners for GluR4 AMPA receptor subunit. Immunoprecipitation of GluR4 and associated proteins was performed using rat cerebellum lysates and an heterologous systems overexpressing GluR4 AMPA receptor subunit. Isolated immuno-complexes were resolved by 1-D SDS-PAGE, and analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS). This approach led to the identification of several interactors, most of which are novel AMPA receptor partners, namely, cytoskeleton proteins, motor proteins, RNA processing proteins which are part of neuronal RNA granules, and kinases, among others. This study unravels new constituents of the macromolecular complex of long-form calcium-permeable AMPA receptors.