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Eukaryotic Mechanosensitive Ion Channels
Published in Tian-Le Xu, Long-Jun Wu, Nonclassical Ion Channels in the Nervous System, 2021
Based on the unique structure of Piezo1/2, it has been proposed that tension-induced expansion of the curved Piezo-membrane area might provide the gating energy for tension-induced channel opening [31,32]. Furthermore, Piezo channels might deform the membrane area outside of their perimeter into a large curved membrane footprint, which might further amplify the mechanosensitivity of the Piezo channels [31]. In line with the unusually curved Piezo channel-membrane system, it has been shown that reconstituted mouse Piezo1 protein in droplet lipid bilayers (containing no other cellular components) opens under asymmetric bilayer-induced membrane curvature, strongly suggesting that Piezo1 is intrinsically mechanosensitive [36]. Thus, on the basis of the signature bowl-shaped feature of the Piezo-membrane system and the electrophysiological characterizations, Piezo channels might adopt a force-from-lipids gating mechanism to enable a versatile response to changes in local curvature and membrane tension.
Chikungunya Fever: Emergence and Reality
Published in Jagriti Narang, Manika Khanuja, Small Bite, Big Threat, 2020
Neelam Yadav, Bennet Angel, Jagriti Narang, Surender Singh Yadav, Vinod Joshi
The dengue NS4A is a hydrophobic protein made of two proteins NS4a and NS4b with molecular weights of 16,000 and 27,000 Da, respectively (Chambers et al., 1989; Speight and Westaway, 1989; Speight et al., 1988). The protein is known to alter the cell membrane curvature (Miller et al., 2007) and induces autophagy. The NS4A acts as a scaffold for the virus replication complex and undergoes oligomerization (Lee et al., 2015). Mutations in NS4A that affect interaction with NS4B either inhibit or reduce virus replication, which shows the significance of NS4A. The interaction of NS4A with NS4B is essential for viral reproduction (Zou et al., 2015). It is also known to act as a cofactor along with the NS5 protein.
Atomic Force Microscopy of Biomembranes
Published in Qiu-Xing Jiang, New Techniques for Studying Biomembranes, 2020
Yi Ruan, Lorena Redondo-Morata, Simon Scheuring
During membrane trafficking, a myriad of proteins act in concert to promote the formation of membrane carriers through membrane remodeling. Previous studies have shown that membrane remodeling proteins perform their functions through several modes. ESCRT-III (Endosomal Sorting Complex Required for Transport) has been implicated in the formation of Intralumenal Vesicles (ILVs) during biogenesis of Multi-Vesicular Bodies (MVBs) by genetic69 and biochemical assays.70,71 This budding process has a topology opposite to the membrane invaginations occurring during endocytosis and membrane traffic at the endoplasmic reticulum or Golgi. In MVBs, the limiting membrane is pushed outwards from the cytoplasm instead of curving inwards. ESCRT-III has been proposed to play a role in membrane deformation72 and fission of ILVs.70 However, it is unclear how ESCRT-III deforms lipid membranes. Because of their polymerization abilities, ESCRT-III proteins (Vps20, Snf7, Vps2, Vps24) have been proposed to generate membrane curvature by scaffolding.73,74
Vesicle formation mechanisms: an overview
Published in Journal of Liposome Research, 2021
If membranes are perfectly flat, then the electric charges that the membrane acquires, can be cancelled out (1998), and membrane curvature leads to a net stress Equation (40). Alternatively, it can be expressed in another terms (Sens and Isambert 2002): b and c are the thickness and the local curvature of a membrane, respectively. From here, we can also write the effective electric field-induced surface tension 1996): 1998), showing most of the electric field around the definite-sized object. On the other hand, for an infinite-sized membrane, the electric field inside the membrane is given by (Sens and Isambert 2002):
The involvement of liquid crystals in multichannel implanted neurostimulators, hearing and ENT infections, and cancer
Published in Acta Oto-Laryngologica, 2019
Chouard Claude-Henri, Christiane Binot, Jean-François Sadoc
The best example concern the cell membrane which is in some sense, a 2-dimensional liquid comprising molecules diffusing in parallel to the surface. It shows planar symmetry between the two interfaces. Perturbation of this symmetry by incorporation of other components such as proteins and cholesterol leads to membrane curvature and invagination. This is a symmetry-breaking between the interior and exterior of the cell. Beyond the membrane, we need to integrate the biological networks giving rise to a given function, exploring other LC cell structures such as multilayers, cubic phases and micelles [27], whether included or not in organelle configurations.
Membrane-binding peptides for extracellular vesicles on-chip analysis
Published in Journal of Extracellular Vesicles, 2020
Alessandro Gori, Alessandro Romanato, Greta Bergamaschi, Alessandro Strada, Paola Gagni, Roberto Frigerio, Dario Brambilla, Riccardo Vago, Silvia Galbiati, Silvia Picciolini, Marzia Bedoni, George G. Daaboul, Marcella Chiari, Marina Cretich
In this regard, sEV membrane is characterised by physical and chemical traits that are peculiar in the extracellular space [1]. sEVs have indeed highly curved membranes, whose outer leaflets typically contain a high amount of anionic, unsaturated phospholipids (e.g. phosphatidylserine) together with the presence of characteristic lipid-packing defects [12–14]. Of note, many proteins are physiologically involved in the dynamic modulation of membrane curvature that occurs during a multitude of cellular processes (including vesicles secretion); in addition, it is further worth highlighting that some of them are able to sense and bind with exquisite selectivity only highly curved membranes [15–18]. These include, among others, the Bin-Amphiphysin-Rvs (BAR) domain of ampiphysin [19], the ArfGAP1 lipid-packing sensor (ALPS) proteins [20], the C2B domain of synaptotagmin-I and the effector domain of the myristoylated alanine-rich C-kinase substrate protein (MARCKS-ED) [21]. Accordingly, peptides derived from membrane-sensing proteins have emerged as convenient, easy-to-synthetise novel molecular probes for targeting highly curved membranes [14,22–24]. In this frame, proposed mechanisms of membrane curvature sensing by protein domains and peptides can be multiple and co-operative (Figure 1). In many cases, the early events of membrane recognition and binding are based on complementary electrostatic interactions between the peptide/protein effector domain and the phospholipids on the outer membrane leaflet, that subsequently can lead to the insertion of the sensing effector into the membrane defects that characterise highly curved membranes [16,21,24]. This mechanism is characteristic of amphipathic peptides. Other recognition pathways were also described [25].