Structural and computational analyses provide the first view of an activated AMPA receptor. Findings published by the Tajkhorshid and Gouaux labs in Cell.
AMPA receptors are transmembrane ion channels that open in the presence of the neurotransmitter glutamate. This can trigger an action potential, and glutamate receptors therefore play critical roles in how neurons communicate. At a synapse between two neurons, AMPA receptors assemble with regulatory proteins, which can change how fast the receptor opens and closes. The most common of these regulatory proteins are TARPs, which act as molecular buoys that surround the receptor in the membrane, and prevent the glutamate-sensing regions from rearranging during receptor desensitization. Structures of TARP-bound AMPA receptors, together with drugs that fully or partially activate the receptor, were solved by cryo-electron microscopy in the lab or Eric Gouaux (OHSU and HHMI). However, these structures were not of sufficient resolution to ‘see’ all the atoms of the receptor, nor could water and ions moving through the channel pore be visualized. Using molecular dynamics simulations, the Tajkhorshid lab computationally modeled the complete structure of the active AMPA receptor with hydrated ions moving through an open pore. Together these findings, published in Cell, show how AMPA receptor regulatory proteins enhance the potency of agonists and alter receptor pore properties, and show how neurotransmitter induces structural rearrangements to open a pore for ions to flow through.
January 26, 2018 All News