Browsing by Author "Smith, T"

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    A chemical glycoproteomics platform reveals O-GlcNAcylation of mitochondrial voltage-dependent anion channel 2.
    (Cell Rep, 2013-10-31) Palaniappan, K; Hangauer, M; Smith, T; Smart, B; Pitcher, A; Cheng, E; Bertozzi, C; Boyce, M
    Protein modification by O-linked β-N-acetylglucosamine (O-GlcNAc) is a critical cell signaling modality, but identifying signal-specific O-GlcNAcylation events remains a significant experimental challenge. Here, we describe a method for visualizing and analyzing organelle- and stimulus-specific O-GlcNAcylated proteins and use it to identify the mitochondrial voltage-dependent anion channel 2 (VDAC2) as an O-GlcNAc substrate. VDAC2(-/-) cells resist the mitochondrial dysfunction and apoptosis caused by global O-GlcNAc perturbation, demonstrating a functional connection between O-GlcNAc signaling and mitochondrial physiology through VDAC2. More broadly, our method will enable the discovery of signal-specific O-GlcNAcylation events in a wide array of experimental contexts.
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    Role of mesons in the electromagnetic form factors of the nucleon
    (Physical Review C - Nuclear Physics, 2010-11-30) Crawford, C; Akdogan, T; Alarcon, R; Bertozzi, W; Booth, E; Botto, T; Calarco, JR; Clasie, B; de Grush, A; Donnelly, TW; Dow, K; Farkhondeh, M; Fatemi, R; Filoti, O; Franklin, W; Gao, H; Geis, E; Gilad, S; Hasell, D; Karpius, P; Kohl, M; Kolster, H; Lee, T; Lomon, E; Maschinot, A; Matthews, J; McIlhany, K; Meitanis, N; Milner, R; Rapaport, J; Redwine, R; Seely, J; Shinozaki, A; Sindile, A; Širca, S; Six, E; Smith, T; Tonguc, B; Tschalaer, C; Tsentalovich, E; Turchinetz, W; Xiao, Y; Xu, W; Zhang, C; Zhou, Z; Ziskin, V; Zwart, T
    The roles played by mesons in the electromagnetic form factors of the nucleon are explored using as a basis a model containing vector mesons with coupling to the continuum together with the asymptotic Q2 behavior of perturbative QCD. Specifically, the vector dominance model (GKex) developed by E. L. Lomon is employed, as it is known to be very successful in representing the existing high-quality data published to date. An analysis is made of the experimental uncertainties present when the differences between the GKex model and the data are expanded in orthonormal basis functions. A main motivation for the present study is to provide insight into how the various ingredients in this model yield the measured behavior, including discussions of when dipole form factors are to be expected or not, of which mesons are the major contributors, for instance, at low Q2 or large distances, and of what effects are predicted from coupling to the continuum. Such insights are first discussed in momentum space, followed by an analysis of how different and potentially useful information emerges when both the experimental and theoretical electric form factors are Fourier transformed to coordinate space. While these Fourier transforms should not be interpreted as "charge distributions," nevertheless the roles played by the various mesons, especially those which are dominant at large or small distance scales, can be explored via such experiment-theory comparisons. © 2010 The American Physical Society.