Building of AMPA-type glutamate receptors in the endoplasmic reticulum and its implication for excitatory neurotransmission.

AMPA-type glutamate receptors (AMPARs), the key elements of fast excitatory neurotransmission in the brain, are receptor ion channels whose core is assembled from pore-forming and three distinct types of auxiliary subunits. While it is well established that this assembly occurs in the endoplasmic reticulum (ER), it has remained largely enigmatic how this receptor-building happens. Here we review recent findings on the biogenesis of AMPARs in native neurons as a multistep production line that is defined and operated by distinct ER-resident helper proteins, and we discuss how impairment of these operators by mutations or targeted gene-inactivation leads to severe phenotypes in both humans and rodents. We suggest that the recent data on AMPAR biogenesis provide new insights into a process that is key to the formation and operation of excitatory synapses and their activity-dependent dynamics, as well as for the operation of the mammalian brain under normal and pathological conditions.