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Santiago de Querétaro, Mexico

Guzman P.,Research Center Estudios Avanzados
Plant Science | Year: 2014

Major components of the ubiquitin proteasome system are the enzymes that operate on the transfer of ubiquitin to selected target substrate, known as ubiquitin ligases. The RING finger is a domain that is present in key classes of ubiquitin ligases. This domain coordinates the interaction with a suitable E2 conjugase and the transfer of ubiquitin from the E2 to protein targets. Additional domains coupled to the same polypeptide are important for modulating the function of these ubiquitin ligases. Plants contain several types of E3 ubiquitin ligases that in many cases have expanded as multigene families. Some families are specific to the plant lineage, whereas others may have a common ancestor among plants and other eukaryotic lineages. Arabidopsis Tóxicos en Levadura (ATLs) and BCA2 zinc finger ATLs (BTLs) are two families of ubiquitin ligases that share some common structural features. These are intronless genes that encode a highly related RING finger domain, and yet during evolutionary history, their mode of gene expansion and function is rather different. In each of these two families, the co-occurrence of transmembrane helices or C2/C2 (BZF finger) domains with a selected variation on the RING finger has been subjected to strong selection pressure in order to preserve their unique domain architectures during evolution. © 2013 Elsevier Ireland Ltd.

Guzman P.,Research Center Estudios Avanzados
Plant Signaling and Behavior | Year: 2012

An abundant class of E3 ubiquitin ligases encodes the RING-finger domain. The RING finger binds to the E2 ubiquitin-conjugating enzyme and brings together both the E2 and substrate. It is predicted that 477 RING finger E3 ligases exist in Arabidopsis thaliana. A particular family among them, named Arabidopsis Tóxicos en Levadura (ATL), consists of 91 members that contain the RING-H2 variation and a hydrophobic domain located at the N-terminal end. Transmembrane E3 ligases are important in several biological processes. For instance, some transmembrane RING finger E3 ligases are main participants in the endoplasmic reticulum-associated degradation pathway that targets misfolded proteins. Functional analysis of a number of ATLs has shown that some of them regulate distinct pathways in plants. Several ATLs have been shown to participate in defense responses, while others play a role in the regulation of the carbon/nitrogen response during post-germinative seedling growth transition, in the regulation of cell death during root development, in endosperm development, or in the transition to flowering under short day conditions. The ATL family has also been instrumental in evolution studies for showing how gene families are expanded in plant genomes. © 2012 Landes Bioscience.

Manko V.S.,Research Center Estudios Avanzados
Progress of Theoretical Physics | Year: 2012

The physical properties of the Tomimatsu-Sato δ = 2 spacetime are analyzed, with emphasis on the issues of the negative mass distribution in this spacetime and the origin of a massless ring singularity. As a by-product of this analysis it is proved analytically that the Kerr spacetime with negative mass always has a massless naked ring singularity off the symmetry axis accompanied by a region with closed timelike curves.

Vargas-Hernandez A.,Research Center Estudios Avanzados | Rodriguez-Alba J.C.,University of Veracruz | Santos-Argumedo L.,Research Center Estudios Avanzados
Journal of Leukocyte Biology | Year: 2014

Btk is the protein affected in XLA, a disease identified as a B cell differentiation defect. Btk is crucial for B cell differentiation and activation, but its role in other cells is not fully understood. This review focuses on the function of Btk in monocytes, neutrophils, and platelets and the receptors and signaling cascades in such cells with which Btk is associated. © Society for Leukocyte Biology.

Fernandez I.,Complutense University of Madrid | Frenking G.,University of Marburg | Merino G.,Research Center Estudios Avanzados
Chemical Society Reviews | Year: 2015

The concept of aromaticity was initially introduced in chemistry to account for the stability, reactivity, molecular structures, and other properties of many unsaturated organic compounds. Despite that, it has been extended to other species with mobile electrons including saturated systems, transition structures, and even inorganic molecules. In this review, we focus on the aromaticity of a particular family of organometallic compounds known as metallabenzenes, which are characterized by the formal replacement of a CH group in benzene by an isolobal transition metal fragment. In addition, aromaticity of related compounds such as heterometallabenzenes is considered as well. To this end, we shall describe herein the insight gained by the available experimental data as well as by the application of the state-of-the-art computational methods developed as descriptors for aromaticity together with a critical evaluation of their performance to quantitatively estimate the strength of aromaticity of these systems. © 2015 The Royal Society of Chemistry.

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