25 research outputs found

    New Structural and Functional Contexts of the Dx[DN]xDG Linear Motif: Insights into Evolution of Calcium-Binding Proteins

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    Binding of calcium ions (Ca2+) to proteins can have profound effects on their structure and function. Common roles of calcium binding include structure stabilization and regulation of activity. It is known that diverse families – EF-hands being one of at least twelve – use a Dx[DN]xDG linear motif to bind calcium in near-identical fashion. Here, four novel structural contexts for the motif are described. Existing experimental data for one of them, a thermophilic archaeal subtilisin, demonstrate for the first time a role for Dx[DN]xDG-bound calcium in protein folding. An integrin-like embedding of the motif in the blade of a β-propeller fold – here named the calcium blade – is discovered in structures of bacterial and fungal proteins. Furthermore, sensitive database searches suggest a common origin for the calcium blade in β-propeller structures of different sizes and a pan-kingdom distribution of these proteins. Factors favouring the multiple convergent evolution of the motif appear to include its general Asp-richness, the regular spacing of the Asp residues and the fact that change of Asp into Gly and vice versa can occur though a single nucleotide change. Among the known structural contexts for the Dx[DN]xDG motif, only the calcium blade and the EF-hand are currently found intracellularly in large numbers, perhaps because the higher extracellular concentration of Ca2+ allows for easier fixing of newly evolved motifs that have acquired useful functions. The analysis presented here will inform ongoing efforts toward prediction of similar calcium-binding motifs from sequence information alone

    A Reflection on the Relation Between Philosophy and Life; Through Hans Blumenberg’s Work

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    O uso de inibidores de apetite por mulheres: um olhar a partir da perspectiva de gênero The use of apetite inhibitors by women: an insight based on the gender perspective

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    O presente estudo teve como objetivo compreender os motivos que levam mulheres adultas a utilizar medicamentos inibidores do apetite e verificar, a partir da ótica de gênero, como se estabelece a relação dessas mulheres com seus próprios corpos. Orientado pelos princípios da pesquisa qualitativa, utilizou como técnicas de construção de dados a entrevista semiestruturada e a observação direta. Participaram como informantes do estudo seis mulheres usuárias de anorexígenos. Os resultados apontaram que as imagens, a publicidade e as redes sociais contribuem significativamente para a criação de padrões de aparência física e de "estilos de vida", cujo modelo preconiza a boa aparência (corpo magro) e a felicidade conjugal. O corpo magro é representado como algo capaz de alterar condições, ou seja, pessoa gorda = pessoa infeliz; e pessoa magra = pessoa feliz. O estudo mostra que é no corpo como lócus que o papel socialmente destinado às mulheres será produzido e reproduzido.<br>The scope of this study was to understand the motives that lead adult women to use appetite inhibitors and to establish, from a gender perspective, how these women relate to their own bodies. It was structured around the principles of qualitative research, and the methods of data collection were semi-structured interviews and direct observation. The informants were six women who used appetite inhibitors. The results indicated that images, publicity and social networks contribute significantly to the creation of new standards of physical appearance as well as lifestyles, which establish appearance (a slim body) and a happy marriage as the desired model. The slim body is represented as something able to alter the temperament of the individual, in other words a fat person is an unhappy person and a slim person is a happy person. The study shows that it is in the body per se that the social role destined for women is produced and reproduced
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