Single-molecule imaging reveals receptor-G protein interactions at cell surface hot spots

G-protein-coupled receptors mediate the biological effects of many hormones and neurotransmitters and are important pharmacological targets. They transmit their signals to the cell interior by interacting with G proteins. However, it is unclear how receptors and G proteins meet, interact and couple. Here we analyse the concerted motion of G-protein-coupled receptors and G proteins on the plasma membrane and provide a quantitative model that reveals the key factors that underlie the high spatiotemporal complexity of their interactions. Using two-colour, single-molecule imaging we visualize interactions between individual receptors and G proteins at the surface of living cells. Under basal conditions, receptors and G proteins form activity-dependent complexes that last for around one second. Agonists specifically regulate the kinetics of receptor-G protein interactions, mainly by increasing their association rate. We find hot spots on the plasma membrane, at least partially defined by the cytoskeleton and clathrin-coated pits, in which receptors and G proteins are confined and preferentially couple. Imaging with the nanobody Nb37 suggests that signalling by G-protein-coupled receptors occurs preferentially at these hot spots. These findings shed new light on the dynamic interactions that control G-protein-coupled receptor signalling

'From bricks to clicks': Hybrid commercial spaces in the landscape of early literacy and learning

In their quest for resources to support children’s early literacy learning and development, parents encounter and traverse different spaces in which discourses and artifacts are produced and circulated. This paper uses conceptual tools from the field of geosemiotics to examine some commercial spaces designed for parents and children which foreground preschool learning and development. Drawing on data generated in a wider study I discuss some of the ways in which the material and virtual commercial spaces of a transnational shopping mall company and an educational toy company operate as sites of encounter between discourses and artifacts about children’s early learning and parents of preschoolers. I consider how companies connect with and ‘situate’ people as parents and customers, and then offer pathways designed for parents to follow as they attempt to meet their very young children’s learning and development needs. I argue that these pathways are both material and ideological, and that are increasingly tending to lead parents to the online commercial spaces of the world wide web. I show how companies are using the online environment and hybrid offline and online spaces and flows to reinforce an image of themselves as authoritative brokers of childhood resources for parents that is highly valuable in a policy climate which foregrounds lifelong learning and school readiness

Administration of the Federal Coal-Mine Safety Act, 1952-60 /

"Covers a report of the Division of Coal Mine Inspection ... as transmitted annually to the Congress."Mode of access: Internet

The Performance Consequences of Manufacturing Outsourcing: Review and Recommendations for Future Research

Many manufacturing firms (e.g. Apple and Nike) now outsource some or all of their manufacturing activities to independent suppliers rather than con- tinuing to undertake them in-house. Clearly these firms perceive this exter- nalisation of production to be a performance-enhancing strategy, but what are the performance consequences in practice? In this chapter, we review and critique the extant academic literature on the performance consequences of manufacturing outsourcing, and note that the empirical findings have yielded mixed results. We argue that outsourcing has potential impacts upon a num- ber of ‘performance’ outcomes, including inter alia financial performance, productivity/efficiency, sales/market share, costs of production, business performance and innovation. We further argue that many of the empirical studies have flawed designs, and make a series of methodological recommen- dations to guide future empirical work

Corporate governance crisis down under: Post-Enron accounting education and research inertia

Abstract Australian and New Zealand accounting academic responses to corporate governance and reporting failures is a story not simply told in the context of high profile international corporate failures such as Enron and WorldCom. This study notes a sequence of major Australian corporate failures that predate Enron and WorldCom. Through research into professional, business and research literature, profession and governmental/regulatory websites, and interviews with senior accounting academics across Australia and New Zealand, it also highlights a tale of limited response by Australian and New Zealand accounting academics and investigates the manifest and latent drivers of this inertia. The corporatisation and commercialisation of universities and related governance processes emerge as root causes of accounting academics' general failure to address recent major breakdowns in corporate governance and reporting in the business world. The paper closes by reviewing opportunities for change in an otherwise embattled environment.Corporate failures, accounting education, corporate governance, accounting academics, teaching, curricula,

Structural flexibility of the Gαs α-helical domain in the β2-adrenoceptor Gs complex

The active-state complex between an agonist-bound receptor and a guanine nucleotide-free G protein represents the fundamental signaling assembly for the majority of hormone and neurotransmitter signaling. We applied single-particle electron microscopy (EM) analysis to examine the architecture of agonist-occupied β2-adrenoceptor (β2AR) in complex with the heterotrimeric G protein Gs (Gαsβγ). EM 2D averages and 3D reconstructions of the detergent-solubilized complex reveal an overall architecture that is in very good agreement with the crystal structure of the active-state ternary complex. Strikingly however, the α-helical domain of Gαs appears highly flexible in the absence of nucleotide. In contrast, the presence of the pyrophosphate mimic foscarnet (phosphonoformate), and also the presence of GDP, favor the stabilization of the α-helical domain on the Ras-like domain of Gαs. Molecular modeling of the α-helical domain in the 3D EM maps suggests that in its stabilized form it assumes a conformation reminiscent to the one observed in the crystal structure of Gαs-GTPγS. These data argue that the α-helical domain undergoes a nucleotide-dependent transition from a flexible to a conformationally stabilized state