1,273 research outputs found
The structural basis of differential DNA sequence recognition by restrictionâmodification controller proteins
Viscoplastic plates
An asymptotic model is constructed to describe the bending of thin sheets, or plates, of viscoplastic fluid described by the HerschelâBulkley constitutive law, which incorporates the von Mises yield condition and a nonlinear viscous stress. The model reduces to a number of previous ones from plasticity theory and viscous fluid mechanics in various limits. It is characterized by a yield criterion proposed by Ilyushin which compactly combines the effect of the bending moment and in-plane stress tensors through three particular invariants. The model is used to explore the bending of loaded flat plates, the deflection of impulsively driven circular plates, and the tension-controlled deflection of loaded beams
Viscoplastic rimming flow instead a rotating cylinder
A theoretical analysis is presented for the flow of a Herschel-Bulkley fluid around the inside surface of a rotating cylinder, at rotation speeds for which the fluid largely collects in a prominent pool in the lower part of the cylinder. The analysis, based on lubrication theory, predicts the steady states typically reached after a small mumber of rotations. The analysis is also modified to consider the drainage of the film around a stationary cylinder, which allows an exploration of the dynamics when a rotating drum is suddenly stopped. The predictions of the theory are compared with experiments in which a Carbopol suspension is rotated inside an acrylic drum
A cryptic RNA-binding domain mediates Syncrip recognition and exosomal partitioning of miRNA targets
Exosomal miRNA transfer is a mechanism for cell-cell communication that is important in the immune response, in the functioning of the nervous system and in cancer. Syncrip/hnRNPQ is a highly conserved RNA-binding protein that mediates the exosomal partition of a set of miRNAs. Here, we report that Syncrip's amino-terminal domain, which was previously thought to mediate protein-protein interactions, is a cryptic, conserved and sequence-specific RNA-binding domain, designated NURR (N-terminal unit for RNA recognition). The NURR domain mediates the specific recognition of a short hEXO sequence defining Syncrip exosomal miRNA targets, and is coupled by a non-canonical structural element to Syncrip's RRM domains to achieve high-affinity miRNA binding. As a consequence, Syncrip-mediated selection of the target miRNAs implies both recognition of the hEXO sequence by the NURR domain and binding of the RRM domains 5Ⲡto this sequence. This structural arrangement enables Syncrip-mediated selection of miRNAs with different seed sequences. Š 2018 The Author(s)
Mechanically operated signalling scaffolds.
Cellular signalling is a complex process and involves cascades of enzymes that, in response to a specific signal, give rise to exact cellular responses. Signalling scaffold proteins organise components of these signalling pathways in space and time to co-ordinate signalling outputs. In this review we introduce a new class of mechanically operated signalling scaffolds that are built into the cytoskeletal architecture of the cell. These proteins contain force-dependent binary switch domains that integrate chemical and mechanical signals to introduce quantised positional changes to ligands and persistent alterations in cytoskeletal architecture providing mechanomemory capabilities. We focus on the concept of spatial organisation, and how the cell organises signalling molecules at the plasma membrane in response to specific signals to create order and distinct signalling outputs. The dynamic positioning of molecules using binary switches adds an additional layer of complexity to the idea of scaffolding. The switches can spatiotemporally organise enzymes and substrates dynamically, with the introduction of âź50â
nm quantised steps in distance between them as the switch patterns change. Together these different types of signalling scaffolds and the proteins engaging them, provide a way for an ordering of molecules that extends beyond current views of the cell
A cryptic RNA-binding domain mediates Syncrip recognition and exosomal partitioning of miRNA targets.
Exosomal miRNA transfer is a mechanism for cellâcell communication that is important in the immune response, in the functioning of the nervous system and in cancer. Syncrip/hnRNPQ is a highly conserved RNA-binding protein that mediates the exosomal partition of a set of miRNAs. Here, we report that Syncripâs amino-terminal domain, which was previously thought to mediate proteinâprotein interactions, is a cryptic, conserved and sequence-specific RNA-binding domain, designated NURR (N-terminal unit for RNA recognition). The NURR domain mediates the specific recognition of a short hEXO sequence defining Syncrip exosomal miRNA targets, and is coupled by a non-canonical structural element to Syncripâs RRM domains to achieve high-affinity miRNA binding. As a consequence, Syncrip-mediated selection of the target miRNAs implies both recognition of the hEXO sequence by the NURR domain and binding of the RRM domains 5Ⲡto this sequence. This structural arrangement enables Syncrip-mediated selection of miRNAs with different seed sequences
IMP1 KH1 and KH2 domains create a structural platform with unique RNA recognition and re-modelling properties
Myocardial blood flow in patients withType 2 Diabetes Mellitus and normal coronary angiography
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