Quantification of interacting cognate odorants with olfactory receptors in nanovesicles

This study aims to improve our understanding of the interaction between olfactory receptors and odorants to develop highly selective biosensing devices. Natural nanovesicles (NVs) from Saccharomyces cerevisiae, ~100 nm in diameter, carrying either the human OR17-40 or the chimpanzee OR7D4 olfactory receptor (OR) tagged with the c-myc epitope at their N-terminus, are presented as model systems to quantify the interaction between odorant and olfactory receptors. The level of expression of olfactory receptors was determined at individual NVs using a novel competitive ELISA immunoassay comparing the values obtained against those from techniques involving the solubilization of cell membrane proteins and the identification of c-myc-carrying receptors. Surface Plasmon Resonance (SPR) measurements on L1 Biacore chips indicate that cognate odorants bind to their Ors, thereby quantifying the approximate number of odorants that interact with a given olfactory receptor. The selectivity of OR17-40-carrying NVs towards helional and OR7D4-carrying NVs towards androstenone has been proven in cross-check experiments with non-specific odorant molecules (heptanal and pentadecalactone, respectively) and in control receptors

Structure of the Homodimeric androgen receptor ligand-binding domain

The androgen receptor (AR) plays a crucial role in normal physiology, development and metabolism as well as in the aetiology and treatment of diverse pathologies such as androgen insensitivity syndromes (AIS), male infertility and prostate cancer (PCa). Here we show that dimerization of AR ligand-binding domain (LBD) is induced by receptor agonists but not by antagonists. The 2.15-Å crystal structure of homodimeric, agonist- and coactivator peptide-bound AR-LBD unveils a 1,000-Å2 large dimerization surface, which harbours over 40 previously unexplained AIS- and PCa-associated point mutations. An AIS mutation in the self-association interface (P767A) disrupts dimer formation in vivo, and has a detrimental effect on the transactivating properties of full-length AR, despite retained hormone-binding capacity. The conservation of essential residues suggests that the unveiled dimerization mechanism might be shared by other nuclear receptors. Our work defines AR-LBD homodimerization as an essential step in the proper functioning of this important transcription factor

Overview of molecular interactions using Biacore

Podeu consultar el llibre complet a: http://hdl.handle.net/2445/32166Surface Plasmon Resonance (SPR) technology is a powerful tool for studying a wide range of different putative interactions. This kind of optical biosensors allow to obtain (in real time and without labelling) quantitative and qualitative information about the kinetics of the surfacebinding process. The most critical points to keep in mind when using the technique are presented, as well as practical examples of applications

Implicació de la calmodulina en la progressió a través de la fase G1 del cicle cel·lular

[spa] Se ha estudiado el papel de la calmodulina (CaM) sobre la regulación de la actividad de la cdk4, cdk2, expresión y localización intracelular de las proteínas que intervienen en la progresión a través de la etapa H1 del ciclo celular. La adición de drogas anti-CaM a un cultivo de células NRK ("normal rat kidney") durante el principio del G1 provoca la inhibición de la actividad cdk4 y cdk2 y también se encuentra la proteína del retinoblastoma hipofosforilada. Los niveles totales de cdk4, ciclina D1, ciclina D2, cicE, p21 y p27 no están afectados por el tratamiento, pero sí que se observó una disminución en la cantidad de cicA y cdc2. La disminución en la actividad de la cdk4 no se debe a un cambio en las proteínas que se le asocian, ni a un cambio en la cantidad de proteínas inhibidoras unidas al complejo ckd4/cicD1. La inhibición de la CaM provoca una translocación del núcleo al citoplasma para la cdk4/cicD1, evitando de este modo que pRb se fosforile bajo el efecto de la droga anti-CaM. Mediante técnicas de inmunoprecipitación, columnas de afinidad y "pull down" se ha demostrado que la cdk4 y la cicD1 se asocian tanto in vivo como in vitro a través de una proteína aceptora de CaM. Como la Hsp90 interactúa con la cdk4 in vivo, y que dicha interacción puede facilitar la translocación de la cdk4 y la cicD1 al núcleo, la Hsp90 es una buena candidata para desempeñar el papel de CaMBP en la transcolocación de la cdk4/ckcD1 al núcleo. Por otro lado se encontró que la p21 coinmunoprecipitaba con la CaM y también en sentido contrario, esta interacción se comprobó que era directa utilizando "pull down". Además se comprobó que la CaM era esencial para acumulación de la p21 en el núcleo

Quantification of interacting cognate odorants with olfactory receptors in nanovesicles

This study aims to improve our understanding of the interaction between olfactory receptors and odorants to develop highly selective biosensing devices. Natural nanovesicles (NVs) from Saccharomyces cerevisiae, ~100 nm in diameter, carrying either the human OR17-40 or the chimpanzee OR7D4 olfactory receptor (OR) tagged with the c-myc epitope at their N-terminus, are presented as model systems to quantify the interaction between odorant and olfactory receptors. The level of expression of olfactory receptors was determined at individual NVs using a novel competitive ELISA immunoassay comparing the values obtained against those from techniques involving the solubilization of cell membrane proteins and the identification of c-myc-carrying receptors. Surface Plasmon Resonance (SPR) measurements on L1 Biacore chips indicate that cognate odorants bind to their Ors, thereby quantifying the approximate number of odorants that interact with a given olfactory receptor. The selectivity of OR17-40-carrying NVs towards helional and OR7D4-carrying NVs towards androstenone has been proven in cross-check experiments with non-specific odorant molecules (heptanal and pentadecalactone, respectively) and in control receptors