AMPA receptor subunits get their share of the pie.

Determining the precise subunit composition of AMPARs in situ has been an enduring challenge. In this issue of Neuron, Lu et al. make significant headway into this pesky problem by using a clever single-cell genetic knockout approach. In a Herculean effort, they provide the field with the completeness of a pie chart outlining the contribution of each AMPAR subunit to basal synaptic transmission at CA1 hippocampus synapses--and we get a pie chart for somatic extrasynaptic receptors, too.