AMPA-type glutamate receptors (AMPARs) are central players in the mammalian brain crucial for a variety of processes including fast excitatory neurotransmission, synapse development and activity-dependent synaptic plasticity that underlies learning and memory. As a key to this pronounced diversity in physiological functions, we have recently provided the first comprehensive analysis of architecture and composition of native AMPARs using novel high-resolution proteomic technologies. Thus, AMPARs in the adult rodent brain are multi-protein complexes of previously unanticipated complexity that are assembled from a pool of 34 different constituents. The majority of these constituents, mostly secreted proteins or transmembrane proteins of different classes, have not yet been related to AMPAR function. Using the newly building blocks of native AMPARs we have started to analyze the significance of this molecular framework for the complex role of AMPARs in excitatory synaptic transmission.