Regulator of G protein–signaling proteins and addictive drugs

Regulator of G protein–signaling (RGS) proteins are a family of more than 30 intracellular proteins that negatively modulate intracellular signaling of receptors in the G protein-coupled receptor family. This family includes receptors for opioids, cannabinoids, and dopamine that mediate the acute effects of addictive drugs or behaviors and chronic effects leading to the development of addictive disease. Members of the RGS protein family, by negatively modulating receptor signaling, influence the intracellular processes that lead to addiction. In turn, addictive drugs control the expression levels of several RGS proteins. This review will consider the distribution and mechanisms of action of RGS proteins, particularly the R4 and R7 families that have been implicated in the actions of addictive drugs, how knowledge of these proteins is contributing to an understanding of addictive processes, and whether specific RGS proteins could provide targets for the development of medications to manage and/or treat addiction.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78669/1/j.1749-6632.2009.05150.x.pd

Resistance to protein synthesis inhibitors in Coprinus cinereus

Cycloheximide, a potent eukaryotic protein synthesis inhibitor (Sisler and Siegel, 1967) was used in a biochemical and genetical investigation of the beisidiomycete fungus, Coprinus cinereus. An optimised polyuridylic acid dependant cell-free polyphenylalanine synthesising system was developed for Coprinus cinereus, in order to identify the cellular component conferring cycloheximide-resistance in two cycloheximide-resistant mutant strains, CY 8.2 and CY9.23 In both of these strains, resistance to cycloheximide was found to be associated with the cytoplasmic ribosome fraction. It was not possible to Identify the particular cytoplasmic ribosomal subunit which conferred cycloheximide-resistance. Analysis of cytoplasmic ribosomal proteins by two-dimensional gel electrophoresis did not reveaú. any difference between the small subunit proteins of CY 8 and CY 8.2. There were a considerable number of differences between the proteins extracted from the large subunit of CY 8 and CY 8.2, and CY 9 and CY9.23. There wan no conclusive evidence to identify a cytoplasmic ribosomal protein associated with cycloheximide resistance although several candidates were proposed. An analysis using carboxymethyl-cellulose chromotography did not Identify any cytoplasmic ribosomal proteins conferring cycloheximide resistance. CY 8.2 was one of 174 cycloheximide-resistant mutant strains produced by the ultraviolet mutagenesis of cycloheximide-sensitive strains, according to a method modified from North (1982). Cycloheximide- resistance in each mutant strain was considered to be conferred a single gene, which in those strains examined, was recessive in heterozygous cycloheximide-resistant dikaryons and diploids . The cycloheximide-resistance mutation in all strains examined belonged to the cy-2 complementation group (North, 1982) and hence were allelic with the resistance gene carried by CY 9.23. A classification of the cycloheximide-resistant mutants was proposed on the basis of their growth responses to cycloheximide

TRICHOTOMOUS CHOICE: A POSSIBLE SOLUTION TO DUAL RESPONSE OBJECTIVES IN DICHOTOMOUS CHOICE CONTINGENT VALUATION QUESTIONS

We investigate the possibility that some respondents to a dichotomous choice question vote YES, even though they would not pay the posted dollar amount in order to register support for the project or policy. A trichotomous choice question format is proposed to determine if allowing respondents the opportunity to vote in favor of a project at an amount less than their bid affects estimated willingness to pay. Using univariate and multivariate tests, we find the trichotomous choice question format reduces the number of YES responses and produces a statistically significant decrease in willingness to pay for an open-space program.Research Methods/ Statistical Methods,

Measuring ligand efficacy at the mu-opioid receptor using a conformational biosensor.

The intrinsic efficacy of orthosteric ligands acting at G-protein-coupled receptors (GPCRs) reflects their ability to stabilize active receptor states (R*) and is a major determinant of their physiological effects. Here, we present a direct way to quantify the efficacy of ligands by measuring the binding of a R*-specific biosensor to purified receptor employing interferometry. As an example, we use the mu-opioid receptor (µ-OR), a prototypic class A GPCR, and its active state sensor, nanobody-39 (Nb39). We demonstrate that ligands vary in their ability to recruit Nb39 to µ-OR and describe methadone, loperamide, and PZM21 as ligands that support unique R* conformation(s) of µ-OR. We further show that positive allosteric modulators of µ-OR promote formation of R* in addition to enhancing promotion by orthosteric agonists. Finally, we demonstrate that the technique can be utilized with heterotrimeric G protein. The method is cell-free, signal transduction-independent and is generally applicable to GPCRs

Legendrian Torus and Cable Links

We give a classification of Legendrian torus links. Along the way, we give the first classification of infinite families of Legendrian links where some smooth symmetries of the link cannot be realized by Legendrian isotopies. We also give the first family of links that are non-destabilizable but do not have maximal Thurston-Bennequin invariant and observe a curious distribution of Legendrian torus knots that can be realized as the components of a Legendrian torus link. This classification of Legendrian torus links leads to a classification of transversal torus links. We also give a classification of Legendrian and transversal cable links of knot types that are uniformly thick and Legendrian simple. Here we see some similarities with the classification of Legendrian torus links but also some differences. In particular, we show that there are Legendrian representatives of cable links of any uniformly thick knot type for which no symmetries of the components can be realized by a Legendrian isotopy, others where only cyclic permutations of the components can be realized, and yet others where all smooth symmetries are realizable.Comment: 67 pages, 19 figure