1,720,993 research outputs found
Tether Me, Tether Me Not-Dynamic Organelle Contact Sites in Metabolic Rewiring
No full textMembrane contact sites (CSs) are specialized cellular regions where distinct organelles are actively positioned very close to each other, at a distance of just a few nanometers. Structurally, CS formation depends on tether proteins that physically link organellar membranes to each other. Functionally, these structures act as hotspots for communication and material transfer. In recent years, we are starting to understand that the cellular CS landscape is not static but instead responds dynamically to diverse metabolic cues. This review describes the interplay between cellular metabolism and CS-based organelle communication and discusses molecular mechanisms of contact modulation in cellular adaptation to changing metabolic requirements
A different kind of love – lipid droplet contact sites
No full textLipid droplets (LDs) store lipids and hence serve as energy reservoir and as a source for building-blocks for the organelle membrane systems. LD biology therefore depends on tight communication with other organelles. The unique architecture of LDs, consisting of a neutral lipid core shielded by a phospholipid-monolayer, is however an obstacle to bulk-exchange of bilayer-bounded vesicles with other organelles. In recent years, it is emerging that contact sites, places where two organelles are positioned in close proximity allowing vesicle-independent communication, are an important way to integrate LDs into the organellar landscape. However, few LD contact sites have been studied in depth and our understanding of their structure, extent and function is only starting to emerge. Here, we highlight recent findings on the functions of LD contact sites and on the proteins involved in their formation and hypothesize about the unique characteristics of the contact sites formed by these intriguing organelles. This article is part of a Special Issue entitled: Recent Advances in Lipid Droplet Biology edited by Rosalind Coleman and Matthijs Hesselink
A Tether Is a Tether Is a Tether: Tethering at Membrane Contact Sites
No full textMembrane contact sites enable interorganelle communication by positioning organelles in close proximity using molecular "tethers." With a growing understanding of the importance of contact sites, the hunt for new contact sites and their tethers is in full swing. Determining just what is a tether has proven challenging. Here, we aim to delineate guidelines that define the prerequisites for categorizing a protein as a tether. Setting this gold standard now, while groups from different disciplines are beginning to explore membrane contact sites, will enable efficient cooperation in the growing field and help to realize a great collaborative opportunity to boost its development
The Vacuole Lipid Droplet Contact Site vCLIP
No full textLipid droplets frequently form contact sites with the membrane of the vacuole, the lysosome-like organelle in yeast. These vacuole lipid droplet (vCLIP) contact sites respond strongly to metabolic cues: while only a subset of lipid droplets is bound to the vacuole when nutrients are abundant, other metabolic states induce stronger contact site formation. Physical lipid droplet-vacuole binding is related to the process of lipophagy, a lipid droplet-specific form of microautophagy. The molecular basis for the formation and function of vCLIP contact sites remained enigmatic for a long time. This knowledge gap was filled when it was found that vCLIP is formed by the structurally related lipid droplet tether proteins Ldo16 and Ldo45, and the vacuolar surface protein Vac8. Ldo45 additionally recruits the phosphatidylinositol transfer protein Pdr16 to vCLIP. Here, we review the literature on the lipid droplet-vacuole contact site in light of the progress in our understanding of its molecular basis and discuss future directions for the field
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Lipid droplet contact sites in health and disease.
No full textAfter having been disregarded for a long time as inert fat drops, lipid droplets (LDs) are now recognized as ubiquitous cellular organelles with key functions in lipid biology and beyond. The identification of abundant LD contact sites, places at which LDs are physically attached to other organelles, has uncovered an unexpected level of communication between LDs and the rest of the cell. In recent years, many disease factors mutated in hereditary disorders have been recognized as LD contact site proteins. Furthermore, LD contact sites are dramatically rearranged in response to infections with intracellular pathogens, as well as under pathological metabolic conditions such as hepatic steatosis. Collectively, it is emerging that LD–organelle contacts are important players in development and progression of disease
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