Modulation of information processing by AMPA receptor auxiliary subunits

AMPA-type glutamate receptors (AMPARs) are key molecules of neuronal communication in our brain. The discovery of AMPAR auxiliary subunits, such as proteins of the TARP, CKAMP and CNIH families, fundamentally changed our understanding of how AMPAR function is regulated. Auxiliary subunits control almost all aspects of AMPAR function in the brain. They influence AMPAR assembly, composition, structure, trafficking, subcellular localization and gating. This influence has important implications for synapse function. In the present review, we first discuss how auxiliary subunits affect the strength of synapses by modulating number and localization of AMPARs in synapses as well as their glutamate affinity, conductance and peak open probability. Next we explain how the presence of auxiliary subunits alters temporal precision and integrative properties of synapses by influencing gating kinetics of the receptors. Auxiliary subunits of the TARP and CKAMP family modulate synaptic short-term plasticity by increasing anchoring of AMPARs in synapses and by altering their desensitization kinetics. We then describe how auxiliary subunits of the TARP, CKAMP and CNIH families are involved in Hebbian and homeostatic plasticity, which can be explained by their influence on surface trafficking and synaptic targeting. In conclusion, the series of studies covered in this review show that auxiliary subunits play a pivotal role in controlling information processing in the brain by modulating synaptic computation.