Browsing by Author "Jayaraman, Vasanthi"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Stargazin Modulation of AMPA Receptors
    (Elsevier, 2016) Shaikh, Sana A.; Dolino, Drew M.; Lee, Garam; Chatterjee, Sudeshna; MacLean, David M.; Flatebo, Charlotte; Landes, Christy F.; Jayaraman, Vasanthi; Applied Physics Graduate Program
    Fast excitatory synaptic signaling in the mammalian brain is mediated by AMPA-type ionotropic glutamate receptors. In neurons, AMPA receptors co-assemble with auxiliary proteins, such as stargazin, which can markedly alter receptor trafficking and gating. Here, we used luminescence resonance energy transfer measurements to map distances between the full-length, functional AMPA receptor and stargazin expressed in HEK293 cells and to determine the ensemble structural changes in the receptor due to stargazin. In addition, we used single-molecule fluorescence resonance energy transfer to study the structural and conformational distribution of the receptor and how this distribution is affected by stargazin. Our nanopositioning data place stargazin below the AMPA receptor ligand-binding domain, where it is well poised to act as a scaffold to facilitate the long-range conformational selection observations seen in single-molecule experiments. These data support a model of stargazin acting to stabilize or select conformational states that favor activation.
  • Thumbnail Image
    Item
    The structure–energy landscape of NMDA receptor gating
    (Springer Nature, 2017) Dolino, Drew M.; Chatterjee, Sudeshna; MacLean, David M.; Flatebo, Charlotte; Bishop, Logan D.C.; Shaikh, Sana A.; Landes, Christy F.; Jayaraman, Vasanthi
    N-Methyl-D-aspartate (NMDA) receptors are the main calcium-permeable excitatory receptors in the mammalian central nervous system. The NMDA receptor gating is complex, exhibiting multiple closed, open, and desensitized states; however, central questions regarding the conformations and energetics of the transmembrane domains as they relate to the gating states are still unanswered. Here, using single-molecule Förster resonance energy transfer (smFRET), we map the energy landscape of the first transmembrane segment of the Rattus norvegicus NMDA receptor under resting and various liganded conditions. These results show kinetically and structurally distinct changes associated with apo, agonist-bound, and inhibited receptors linked by a linear mechanism of gating at this site. Furthermore, the smFRET data suggest that allosteric inhibition by zinc occurs by an uncoupling of the agonist-induced changes at the extracellular domains from the gating motions leading to an apo-like state, while dizocilpine, a pore blocker, stabilizes multiple closely packed transmembrane states.