1. Selective, rapid and optically switchable regulation of protein function in live mammalian cells.

    Nature Chemistry 7(7):554 (2015) PMID 26100803 PMCID PMC4673907

    The rapid and selective regulation of a target protein within living cells that contain closely related family members is an outstanding challenge. Here we introduce genetically directed bioorthogonal ligand tethering (BOLT) and demonstrate selective inhibition (iBOLT) of protein function. In iB...
  2. Biophysical mechanism of T-cell receptor triggering in a reconstituted system.

    Nature 487(7405):64 (2012) PMID 22763440 PMCID PMC3393772

    A T-cell-mediated immune response is initiated by the T-cell receptor (TCR) interacting with peptide-bound major histocompatibility complex (pMHC) on an infected cell. The mechanism by which this interaction triggers intracellular phosphorylation of the TCR, which lacks a kinase domain, remains ...
  3. The T cell receptor triggering apparatus is composed of monovalent or monomeric proteins.

    Journal of Biological Chemistry 286(37):31993 (2011) PMID 21757710 PMCID PMC3173209

    Understanding the component stoichiometry of the T cell antigen receptor (TCR) triggering apparatus is essential for building realistic models of signal initiation. Recent studies suggesting that the TCR and other signaling-associated proteins are preclustered on resting T cells relied on measur...
  4. A new pathway of CD5 glycoprotein-mediated T cell inhibition dependent on inhibitory phosphorylation of Fyn kinase.

    Journal of Biological Chemistry 286(35):30324 (2011) PMID 21757751 PMCID PMC3162391

    Triggering of the T cell receptor initiates a signaling cascade resulting in the activation of the T cell. These signals are integrated alongside those resulting from the triggering of other receptors whose function is to modulate the overall response. CD5 is an immunotyrosine-based inhibition m...
  5. Distinctive properties of the hyaluronan-binding domain in the lymphatic endothelial receptor Lyve-1 and their implications for receptor function.

    Journal of Biological Chemistry 285(14):10724 (2010) PMID 19887450 PMCID PMC2856280

    The lymphatic endothelial hyaluronan (HA) receptor Lyve-1 is a member of the Link protein superfamily most similar to the leukocyte HA receptor CD44. However, the structure of Lyve-1 and the nature of its interaction with ligand are obscure. Here we present new evidence that Lyve-1 is functional...
  6. The platelet receptor CLEC-2 is active as a dimer.

    Biochemistry (Washington) 48(46):10988 (2009) PMID 19824697

    The platelet receptor CLEC-2 binds to the snake venom toxin rhodocytin and the tumor cell surface protein podoplanin. Binding of either of these ligands promotes phosphorylation of a single tyrosine residue in the YXXL motif in the intracellular domain of CLEC-2. Phosphorylation of this tyrosine...
  7. DySCo: quantitating associations of membrane proteins using two-color single-molecule tracking.

    Biophysical Journal 97(4):L5 (2009) PMID 19686638 PMCID PMC2726305

    We present a general method called dynamic single-molecule colocalization for quantitating the associations of single cell surface molecules labeled with distinct autofluorescent proteins. The chief advantages of the new quantitative approach are that, in addition to stable interactions, it is c...
  8. Acute nicotine reduces and repeated nicotine increases spontaneous activity in male and female Lewis rats.

    Pharmacology Biochemistry and Behavior 91(1):150 (2008) PMID 18644403 PMCID PMC2638993

    The Lewis (LEW) strain of rat appears more sensitive to nicotine than other strains in self-administration, conditioned place preference, and drug discrimination behavioral studies. The present study sought to further evaluate the behavioral effects of chronic nicotine treatment in the LEW strai...
  9. The effects of acute and repeated nicotine doses on spontaneous activity in male and female Sprague Dawley rats: analysis of brain area epibatidine binding and cotinine levels.

    Pharmacology Biochemistry and Behavior 89(3):424 (2008) PMID 18313740

    Previous research in this laboratory has shown that nicotine's effects on spontaneous activity are contingent on individual differences, attenuating activity in high active rats and increasing it in low active rats. This study was designed to further evaluate this phenomenon, and to compare it w...
  10. Ferroportin: lack of evidence for multimers.

    Blood Cells, Molecules, and Diseases 40(3):360 (2008) PMID 17977032

    Ferroportin is a multi-transmembrane glycoprotein that mediates iron export from cells. Mutations in ferroportin are linked to type IV hemochromatosis, a dominantly inherited disorder of iron metabolism. Multimers of ferroportin, whose existence may relate to the dominant inheritance pattern of ...
  11. Single-molecule level analysis of the subunit composition of the T cell receptor on live T cells.

    PNAS 104(45):17662 (2007) PMID 17971442 PMCID PMC2077052

    The T cell receptor (TCR) expressed on most T cells is a protein complex consisting of TCRalphabeta heterodimers that bind antigen and cluster of differentiation (CD) 3epsilondelta, epsilongamma, and zetazeta dimers that initiate signaling. A long-standing controversy concerns whether there is o...
  12. A rigorous experimental framework for detecting protein oligomerization using bioluminescence resonance energy transfer.

    Nature Methods 3(12):1001 (2006) PMID 17086179

    Bioluminescence resonance energy transfer (BRET), which relies on nonradiative energy transfer between luciferase-coupled donors and GFP-coupled acceptors, is emerging as a useful tool for analyzing the quaternary structures of cell-surface molecules. Conventional BRET analyses are generally don...
  13. Neurochemical and behavioral effects of bupropion and mecamylamine in the presence of nicotine.

    Brain Research 1117(1):18 (2006) PMID 16949560

    The primary mechanism of action of bupropion, a smoking cessation drug, is commonly believed to involve the dopaminergic system although evidence exists that bupropion also has effects at nicotinic acetylcholine receptors (nAChRs). This study evaluated the disruptive effects of nicotine on respo...
  14. Nicotinic receptor inactivation after acute and repeated in vivo nicotine exposures in rats.

    Brain Research 1086(1):98 (2006) PMID 16626643

    Nicotine tolerance is often accompanied by an upregulation of brain area nicotinic acetylcholine receptors (nAChRs) in both animal and human subjects. This upregulation has been hypothesized to result from repeated or prolonged exposures of these receptors to nicotine. To explore this further, t...
  15. Evidence of cellular nicotinic receptor desensitization in rats exhibiting nicotine-induced acute tolerance.

    Psychopharmacology 184(3-4):306 (2006) PMID 16010542

    Individuals vary in their susceptibility to nicotine addiction. However, there is little evidence that behavioral sensitivity to nicotine is dependent upon the functional state of nicotinic cholinergic receptors (nAChRs). To determine the relationship between in vivo pharmacological desensitizat...
  16. Withdrawal from chronic nicotine administration impairs contextual fear conditioning in C57BL/6 mice.

    Journal of Neuroscience 25(38):8708 (2005) PMID 16177040 PMCID PMC2697573

    The effects of acute nicotine administration (0.09 mg/kg nicotine), chronic nicotine administration (6.3 mg/kg/d nicotine for 14 d), and withdrawal from chronic nicotine administration on fear conditioning in C57BL/6 mice were examined. Mice were trained using two coterminating conditioned stimu...
  17. Crystal structure of a soluble CD28-Fab complex.

    Nature Immunology 6(3):271 (2005) PMID 15696168

    Naive T cell activation requires signaling by the T cell receptor and by nonclonotypic cell surface receptors. The most important costimulatory protein is the monovalent homodimer CD28, which interacts with CD80 and CD86 expressed on antigen-presenting cells. Here we present the crystal structur...
  18. Differential behavioral responses to nicotine in Lewis and Fischer-344 rats.

    Pharmacology Biochemistry and Behavior 80(1):87 (2005) PMID 15652384

    Individual and strain variability in the effects of nicotine suggests the involvement of a genetic component in nicotinic cholinergic receptor (nAChR) function, which may help explain nicotine's variable behavioral and pharmacological effects in different individuals. The present study evaluated...