Protein complex analysis of native brain potassium channels by proteomics.

TREK potassium channels belong to a family of channel subunits with two-pore domains (K(2P)). TREK1 knockout mice display impaired polyunsaturated fatty acid-mediated protection against brain ischemia, reduced sensitivity to volatile anesthetics, resistance to depression and altered perception of pain. Recently, we isolated native TREK1 channels from mouse brain and identified their specific components by mass spectrometry. Among the identified partners, the A-Kinase Anchoring Protein AKAP150 binds to a regulatory domain of TREK1 and acts as a molecular switch. It transforms low activity, outwardly rectifying TREK1 currents into robust leak conductances resistant to stimulation by arachidonic acid, membrane stretch and acidification. Inhibition of the TREK1/AKAP150 channel by Gs-coupled receptors is as extensive as for TREK1 alone (but faster) whereas inhibition of TREK1/AKAP150 by Gq-coupled receptors is reduced. Furthermore, the association of AKAP150 with TREK1 channels integrates them into postsynaptic scaffolds where G protein-coupled membrane receptors and channels dock simultaneously. This chapter describes the proteomic approach used to study the composition of native TREK1 channels and point out its advantages and limitations over more classical methods (two-hybrid screenings in the yeast and bacteria or GST-pull down).