Search results for "mem"
showing 10 items of 7971 documents
The Extracellular δ-Domain is Essential for the Formation of CD81 Tetraspanin Webs
2014
AbstractCD81 is a ubiquitously expressed member of the tetraspanin family. It forms large molecular platforms, so-called tetraspanin webs that play physiological roles in a variety of cellular functions and are involved in viral and parasite infections. We have investigated which part of the CD81 molecule is required for the formation of domains in the cell membranes of T-cells and hepatocytes. Surprisingly, we find that large CD81 platforms assemble via the short extracellular δ-domain, independent from a strong primary partner binding and from weak interactions mediated by palmitoylation. The δ-domain is also essential for the platforms to function during viral entry. We propose that, ins…
In vitro studies on the activation of the hepatitis C virus NS3 proteinase by the NS4A cofactor.
1996
AbstractProteolytic processing of the nonstructural proteins of the hepatitis C virus (HCV) is mediated by two viral proteinases: the NS2-3 proteinase cleaving at the NS2/3 junction and the NS3 serine-type proteinase responsible for processing at the NS3/4A, NS4A/B, NS4B/5A, and NS5A/B sites. Activity of the NS3 proteinase is modulated by NS4A. In the absence of this cofactor processing at the NS3-dependent sites does not occur or, in the case of the NS5A/B junction, is poor but increased when NS4A is present. Although recent studies demonstrated that proteinase activation requires direct interaction between NS3 and NS4A, the mechanism by which NS4A exerts the activation function is not kno…
SARS-CoV-2 envelope protein topology in eukaryotic membranes
2020
Coronavirus E protein is a small membrane protein found in the virus envelope. Different coronavirus E proteins share striking biochemical and functional similarities, but sequence conservation is limited. In this report, we studied the E protein topology from the new SARS-CoV-2 virus both in microsomal membranes and in mammalian cells. Experimental data reveal that E protein is a single-spanning membrane protein with the N-terminus being translocated across the membrane, while the C-terminus is exposed to the cytoplasmic side (Nt lum /Ct cyt ). The defined membrane protein topology of SARS-CoV-2 E protein may provide a useful framework to understand its interaction with other viral and ho…
Clathrin- and Caveolin-Independent Entry of Human Papillomavirus Type 16—Involvement of Tetraspanin-Enriched Microdomains (TEMs)
2008
BACKGROUND: Infectious entry of human papillomaviruses into their host cells is an important step in the viral life cycle. For cell binding these viruses use proteoglycans as initial attachment sites. Subsequent transfer to a secondary receptor molecule seems to be involved in virus uptake. Depending on the papillomavirus subtype, it has been reported that entry occurs by clathrin- or caveolin-mediated mechanisms. Regarding human papillomavirus type 16 (HPV16), the primary etiologic agent for development of cervical cancer, clathrin-mediated endocytosis was described as infectious entry pathway. METHODOLOGY/PRINCIPAL FINDINGS: Using immunofluorescence and infection studies we show in contra…
Tumor targeting of baculovirus displaying a lymphatic homing peptide.
2008
Background Tumor-associated cells and vasculature express attractive molecular markers for site-specific vector targeting. To attain tumor-selective tropism, we recently developed a baculovirus vector displaying the lymphatic homing peptide LyP-1, originally identified by ex vivo/in vivo screening of phage display libraries, on the viral envelope by fusion to the transmembrane anchor of vesicular stomatitis virus G-protein. Methods In the present study, we explored the specificity and kinetics of viral binding and internalization as well as in vivo tumor homing of the LyP-1 displaying virus to elucidate the applicability of baculovirus for targeted therapies. Results We demonstrated that th…
Building a political image on Instagram: A study of the personal profile of Santiago Abascal (Vox) in 2018
2020
Due to Instagram’s growing popularity in Spain, politicians have also begun to turn to this social network increasingly more. Accordingly, this paper analyses the visual and textual discourse of 259 posts published throughout 2018 on the personal Instagram profile of Santiago Abascal, the leader of the party Vox. Insofar as he is the Spanish politician with the highest number of followers on Instagram, the aim here is to analyse how he uses this social network in order to identify possible strategies that justify his growing number of followers. In the analysis, special attention was paid to aspects that might have contributed to the (self)presentation of Abascal and the promotion of his pa…
Sustained attention required for effective dimension-based retro-cue benefit in visual working memory
2023
In visual working memory (VWM) tasks, participants’ performances can be improved through the use of dimension-based retro-cues, which direct internal attention to prioritize a particular dimension (e.g., color or orientation) of VWM representations even after the stimuli disappear. This phenomenon is known as the dimension-based retro-cue benefit (RCB). The present study investigates whether sustained attention is required for the dimension-based RCB by inserting interference or interruption between the retro-cue and the test array to distract attention. We tested the effects of perceptual interference or cognitive interruption on dimension-based RCB when the interference (Experiments 1 and…
视觉工作记忆存储的表征单位 [The Representation Unit of Visual Working Memory]
2022
The visual working memory is a limited storage system in which people could flexibly process the representations to complete the task. Among studies on the capacity of visual working memory, the representation unit is a prior subject. Previous research employs the change-detection paradigm and the recall paradigm to explore the nature of representations when features of diverse dimensions and different-level features of the same dimension are stored in the visual working memory. These studies elicit two binary hypotheses: the object-based representation hypothesis backs that those diverse features are bound on the object and form a whole, while the feature-based representation hypothesis su…
Visual working memory resource allocation mechanism in consolidation and maintenance phase
2018
Visual working memory (VWM) is a system for actively maintaining visual information to meet the needs of an ongoing task. It allows individuals to store visual input information from a complex outside environment and provides storage space as an information buffer platform to help integrate information into a continuous visual experience. This research examined the consolidation and maintenance phase of the VWM resource allocation mechanism. Four aspects of this issue were investigated. First, resource allocation in VWM consolidation was investigated for different materials, and it was determined whether VWM resources were allocated in a serial manner for orientation materials but in a limi…
The mechanism of retro-cue effect in visual working memory : Cognitive phase separation
2020
Retro-cue effect (RCE) refers to the phenomenon that individuals can use retro-cues to improve their visual working memory (VWM) performance of target items after memory stimuli disappear. To explain the mechanism of RCE in VWM, five different hypotheses have been proposed by previous studies: the hypothesis of enhancing target representations, the hypothesis of forgetting non-target representations, the hypothesis of preventing memory degradation, the hypothesis of preventing interference from probe array and the hypothesis of cognitive phase separation. Although RCE has been repeatedly observed in previous studies, the mechanism of RCE remains unclear. In this study, we conducted three ex…