High affinity binding of the peptide agonist TIP-39 to the parathyroid hormone 2 (PTH₂) receptor requires the hydroxyl group of Tyr-318 on transmembrane helix 5

TIP39 (“tuberoinfundibular peptide of 39 residues”) acts via the parathyroid hormone 2 receptor, PTH₂, a Family B G protein-coupled receptor (GPCR). Despite the importance of GPCRs in human physiology and pharmacotherapy, little is known about the molecular details of the TIP39-PTH₂ interaction. To address this, we utilised the different pharmacological profiles of TIP39 and PTH(1-34) at PTH₂ and its related receptor PTH₁: TIP39 being an agonist at the former but an antagonist at the latter, while PTH(1-34) activates both. A total of 23 site-directed mutations of PTH₂, in which residues were substituted to the equivalent in PTH₁, were made and pharmacologically screened for agonist activity. Follow-up mutations were analysed by radioligand binding and cAMP assays. A model of the TIP39-PTH₂ complex was built and analysed using molecular dynamics. Only Tyr318-Ile displayed reduced TIP39 potency, despite having increased PTH(1-34) potency, and further mutagenesis and analysis at this site demonstrated that this was due to reduced TIP39 affinity at Tyr318-Ile (pIC50 = 6.01±0.03) compared with wild type (pIC₅₀ = 7.81±0.03). The hydroxyl group of the Tyr-318’s side chain was shown to be important for TIP39 binding, with the Tyr318-Phe mutant displaying 13-fold lower affinity and 35-fold lower potency compared with wild type. TIP39 truncated by up to 5 residues at the N-terminus was still sensitive to the mutations at Tyr-318, suggesting that it interacts with a region within TIP39(6-39). Molecular modelling and molecular dynamics simulations suggest that the selectivity is based on an interaction between the Tyr-318 hydroxyl group with the carboxylate side chain of Asp-7 of the peptide

La cultura nacional y su impacto en los negocios: El caso chileno

El objetivo de este artículo es analizarel impacto de la cultura nacional enlos negocios. Uno de los investigadoresmás destacados en el análisis dela cultura nacional es Geert Hofstede(1980). Él identificó cuatro dimensionesde la cultura nacional: distanciade poder, aversión a la incertidumbre,individualismo y masculinidad.Fernández et al. (1997) midieronestas cuatro dimensiones en Chile,caracterizando a los chilenos en esascuatro dimensiones. Revisando laevidencia empírica chilena, en esteartículo se analizan los principalesefectos que las dimensiones de Hofstedetienen en la administración, losrecursos humanos y el marketing.Este artículo ofrece varios ejemplosde cómo las dimensiones culturalesafectan las prácticas en las organizacionesy es un fuerte argumento parahacer consideraciones culturales en laplanificación estratégica.Cultura nacional, dimensiones culturales,distancia cultural, organizacioneschilenas

Receptor activity modifying protein-directed G protein signaling specificity for the calcitonin gene-related peptide family of receptors

The calcitonin gene-related peptide (CGRP) family of G protein-coupled receptors (GPCRs) is formed through association of the calcitonin receptor-like receptor (CLR) and one of three receptor activitymodifying proteins (RAMPs). Binding of one of the three peptide ligands, CGRP, adrenomedullin (AM) or intermedin/adrenomedullin2 (AM2) is well known to result in a Gαs-mediated increase in cAMP. Here we use modified yeast strains that couple receptor activation to cell growth, via chimeric yeast/Gα subunits, and HEK-293 cells to characterize the effect of different RAMP and ligand combinations on this pathway. We not only demonstrate functional couplings to both Gα$_{s}$ and Gα$_{q}$ but also identify a Gα$_{i}$ component to CLR signaling in both yeast and HEK- 293 cells, which is absent in HEK-293S cells. We show that the CGRP family of receptors displays both ligand and RAMP-dependent signaling bias between Gα$_{s}$, Gα$_{i}$ and Gα$_{q/11}$ pathways. The results are discussed in the context of RAMP interactions probed through molecular modelling and molecular dynamics simulations of the RAMP-GPCR-G protein complexes. This study further highlights the importance of RAMPs to CLR pharmacology, and to bias in general, as well as identifying the importance of choosing an appropriate model system for the study of GPCR pharmacology.This work was supported by the National Heart Foundation of New Zealand (H.W.), the School of Biological Sciences, University of Auckland seed fund (H.W.), the BBSRC (G.L. - BB/M00015X/1), (D.P. - BB/M000176/1), (C.A.R. - BB/M006883/1), a BBSRC Doctoral Training Partnership (M.H. – BB/JO14540/1), an MRC Doctoral Training Partnership (I.W. - MR/J003964/1), a Warwick Impact Fund (C.W., G.L.), a Warwick Research Development Fund (C.W., G.L.) grant number (RD13301) and the Warwick Undergraduate Research Scholarship Scheme (A.S and R.H).This is the author accepted manuscript. It is currently under an indefinite embargo pending publication by the American Society for Biochemistry and Molecular Biology

Marcas Privadas en Chile: un análisis preliminar de la percepción del consumidor

Este Documento es producto del trabajo de Académicos del Departamento de Administració

A Pathway Model to Understand the Evolution of Spike Protein Binding to ACE2 in SARS-CoV-2 Variants

After the SARS-CoV-2 Wuhan variant that gave rise to the pandemic, other variants named Delta, Omicron, and Omicron-2 sequentially became prevalent, with mutations spread around the viral genome, including on the spike (S) protein; in order to understand the resultant in gains in infectivity, we interrogated in silico both the equilibrium binding and the binding pathway of the virus’ receptor-binding domain (RBD) to the angiotensin-converting enzyme 2 (ACE2) receptor. We interrogated the molecular recognition between the RBD of different variants and ACE2 through supervised molecular dynamics (SuMD) and classic molecular dynamics (MD) simulations to address the effect of mutations on the possible S protein binding pathways. Our results indicate that compensation between binding pathway efficiency and stability of the complex exists for the Omicron BA.1 receptor binding domain, while Omicron BA.2′s mutations putatively improved the dynamic recognition of the ACE2 receptor, suggesting an evolutionary advantage over the previous strains

Genetically encoded photocross-linkers determine the biological binding site of exendin-4 peptide in the N-terminal domain of the intact human glucagon-like peptide-1 receptor (GLP-1R)

The glucagon-like peptide-1 receptor (GLP-1R) is a key therapeutic target in the management of type II diabetes mellitus, with actions including regulation of insulin biosynthesis and secretion, promotion of satiety, and preservation of β-cell mass. Like most class B G protein-coupled receptors (GPCRs), there is limited knowledge linking biological activity of the GLP-1R with the molecular structure of an intact, full-length, and functional receptor·ligand complex. In this study, we have utilized genetic code expansion to site-specifically incorporate the photoactive amino acid p-azido-l-phenylalanine (azF) into N-terminal residues of a full-length functional human GLP-1R in mammalian cells. UV-mediated photolysis of azF was then carried out to induce targeted photocross-linking to determine the proximity of the azido group in the mutant receptor with the peptide exendin-4. Cross-linking data were compared directly with the crystal structure of the isolated N-terminal extracellular domain of the GLP-1R in complex with exendin(9–39), revealing both similarities as well as distinct differences in the mode of interaction. Generation of a molecular model to accommodate the photocross-linking constraints highlights the potential influence of environmental conditions on the conformation of the receptor·peptide complex, including folding dynamics of the peptide and formation of dimeric and higher order oligomeric receptor multimers. These data demonstrate that crystal structures of isolated receptor regions may not give a complete reflection of peptide/receptor interactions and should be combined with additional experimental constraints to reveal peptide/receptor interactions occurring in the dynamic, native, and full-length receptor state

Brand Personality in Chile: a combined emic-etic approach

The purpose of our study is to extend previous work on brand personality (Aaker 1997). While following Aaker’s recommended methodology, we did so in the context of an emerging market economy such as Chile, and using a combined emic-etic research approach. Then, we investigated the cross-cultural applicability of the construct and we also look into the applicability of the measurement instrument developed by Aaker (1997). After several validation studies, six brand personality dimensions were found instead of the original North American based study, with Tradition being the new Chilean dimension. This is consistent with previous work finding nation-specific dimensions in Japan, Spain, and France (i.e. Aaker, Benet-Martinez, Garolera, 2001; Koebel and Landwein, 1999). Insights for the understanding and management of brand images in international contexts, complementing parallel work done in other developed nations are derived.El propósito de este estudio es extender el trabajo existente en el area de personalidad de marca iniciado por Aaker (1997). Se sigue el método sugerido por Aaker, pero en el contexto de una economía de Mercado emergente como Chile, y usando un enfoque combinado emico-etico de investigación. Por ende se investiga la aplicabilidad cros-cultural del constructo personalidad de marca, y del instrumento desarrollado por Aaker en el contexto norteamericano. Después de varios estudios de validación, se encontraron 6 dimensiones de la personalidad de marca, en comparación a los 5 originales en el instrumento de EE.UU., 5 de ellos con bastantes grados de similitude y una sexta dimension denominada Tradición, como particular a la realidad Chilena. Estos resultados son consistentes con estudios previos que ahn encontrado dimensiones específicas a naciones (culturas) cen Japón, España, y Francia (i.e. Aaker, Benet-Martinez, Garolera, 2001; Koebel and Landwein, 1999). Se presentarn implicancias para el entendimiento y gestión de las marcas, en contextos internacionales, y para estudios futuros

Understanding the molecular functions of the second extracellular loop (ECL2) of the calcitonin gene-related peptide (CGRP) receptor using a comprehensive mutagenesis approach

The extracellular loop 2 (ECL2) region is the most conserved of the three ECL domains in family B G protein-coupled receptors (GPCRs) and has a fundamental role in ligand binding and activation across the receptor super-family. ECL2 is fundamental for ligand-induced activation of the calcitonin gene related peptide (CGRP) receptor, a family B GPCR implicated in migraine and heart disease. In this study we apply a comprehensive targeted non-alanine substitution analysis method and molecular modelling to the functionally important residues of ECL2 to reveal key molecular interactions. We identified an interaction network between R274/Y278/D280/W283. These amino acids had the biggest reduction in signalling following alanine substitution analysis and comprise a group of basic, acidic and aromatic residues conserved in the wider calcitonin family of class B GPCRs. This study identifies key and varied constraints at each locus, including diverse biochemical requirements for neighbouring tyrosine residues and a W283H substitution that recovered wild-type (WT) signalling, despite the strictly conserved nature of the central ECL2 tryptophan and the catastrophic effects on signalling of W283A substitution. In contrast, while the distal end of ECL2 requires strict conservation of hydrophobicity or polarity in each position, mutation of these residues never has a large effect. This approach has revealed linked networks of amino acids, consistent with structural models of ECL2 and likely to represent a shared structural framework at an important ligand-receptor interface that is present across the family B GPCRs

¿Es Sexista la Publicidad Gráfica Chilena? Comparando la Evidencia Chilena con la Internacional

Diversos autores han establecido que los medios de comunicación ocupan una posición central en la vida de las personas, siendo uno de los principales (aunque no los únicos) responsables de las concepciones que se construyen acerca del mundo en que se vive (McQuail, 2000)

The circularly permuted globin domain of Androglobin

Androglobin, is a recently discovered circularly permuted, multi-domain is hemoglobin. Using a remote homologue alignment method, coupled with molecular modelling and molecular dynamics, we identified the alignment to other hemoglobins. This guided the first stable recombinant expression of an androglobin domain and the first structural and biochemical characterization of the globin domain of androglobin, which is split by an IQ domain. Tyrosine is found in place of the highly conserved phenylalanine that resides in the highly conserved CD1 position, a structural feature unknown in eukaryotes but common in prokaryotic globins. As expressed, the heme iron is hexacoordinate in the ferrous form but partially pentacoordinate in the ferric form. Exceptional in the globin superfamily, but similar to other hemoproteins such as cytochrome c’, the heme iron binds nitric oxide as a five coordinate complex. This work expands our knowledge of the fundamental chemistry of this hitherto elusive medically important protein