scholarly journals Phase separation of Ede1 promotes the initiation of endocytic events

2019 ◽  
Author(s):  
Mateusz Kozak ◽  
Marko Kaksonen
Keyword(s):  
Plasma Membrane ◽  
Phase Separation ◽  
Coiled Coil ◽  
Dynamic Network ◽  
Lipid Binding ◽  
Core Region ◽  
Initiation Factor ◽  
Major Pathway ◽  
The Core ◽  
Endocytic Proteins

AbstractClathrin-mediated endocytosis is a major pathway that eukaryotic cells use to produce transport vesicles from the plasma membrane. The assembly of the endocytic coat is initiated by a dynamic network of weakly interacting proteins, but the exact mechanism of initiation is unknown. Ede1, the yeast homologue of mammalian Eps15, is one of the early-arriving endocytic proteins and a key initiation factor. In the absence of Ede1, most other early endocytic proteins lose their punctate localization and the frequency of endocytic initiation is decreased. We show here that in mutants with increased amounts of cytoplasmic Ede1, the excess protein forms large condensates which exhibit properties of phase separated liquid protein droplets. These Ede1 condensates recruit many other early-arriving endocytic proteins. Their formation depends on the core region of Ede1 that contains a coiled coil and a low-complexity domain. We demonstrate that Ede1 core region is essential for the endocytic function of Ede1. The core region can also promote clustering of a heterologous lipid-binding domain into discrete sites on the plasma membrane that initiate endocytic events. We propose that the clustering of the early endocytic proteins and cargo depend on phase separation mediated by Ede1.

scholarly journals Num1 anchors mitochondria to the plasma membrane via two domains with different lipid binding specificities

2016 ◽  
Vol 213 (5) ◽  
pp. 513-524 ◽  
Author(s):  
Holly A. Ping ◽  
Lauren M. Kraft ◽  
WeiTing Chen ◽  
Amy E. Nilles ◽  
Laura L. Lackner
Keyword(s):  
Plasma Membrane ◽  
Specific Binding ◽  
Coiled Coil ◽  
Lipid Binding ◽  
General Mechanism ◽  
Cell Cortex ◽  
Pleckstrin Homology Domain ◽  
Binding Domains ◽  
Coiled Coil Domain ◽  
Mitochondrial Distribution

The mitochondria–ER cortex anchor (MECA) is required for proper mitochondrial distribution and functions by tethering mitochondria to the plasma membrane. The core component of MECA is the multidomain protein Num1, which assembles into clusters at the cell cortex. We show Num1 adopts an extended, polarized conformation. Its N-terminal coiled-coil domain (Num1CC) is proximal to mitochondria, and the C-terminal pleckstrin homology domain is associated with the plasma membrane. We find that Num1CC interacts directly with phospholipid membranes and displays a strong preference for the mitochondria-specific phospholipid cardiolipin. This direct membrane interaction is critical for MECA function. Thus, mitochondrial anchoring is mediated by a protein that interacts directly with two different membranes through lipid-specific binding domains, suggesting a general mechanism for interorganelle tethering.

scholarly journals Protein 4.1R self-association: identification of the binding domain

2006 ◽  
Vol 400 (3) ◽  
pp. 457-465
Author(s):  
Carmen M. Pérez-Ferreiro ◽  
Eva Lospitao ◽  
Isabel Correas
Keyword(s):  
Plasma Membrane ◽  
Core Region ◽  
Binding Domain ◽  
Intramolecular Interactions ◽  
Actin Network ◽  
Protein 4.1 ◽  
The Core ◽  
Self Association ◽  
Protein 4.1R

Erythroid protein 4.1 (4.1R) stabilizes the spectrin–actin network and anchors it to the plasma membrane. To contribute to the characterization of non-erythroid protein 4.1R, we used sedimentation, pull-down and co-immunoprecipitation assays to investigate the ability of protein 4.1R to establish inter-/intra-molecular associations. We demonstrated that the small 4.1R isoforms of 60 kDa (4.1R60), but not the larger isoforms of 80 and 135 kDa (4.1R80 and 4.1R135), were self-associated, and that a domain contained in all 4.1R isoforms, the core region, was responsible for 4.1R self-association. Results from denaturing–renaturing experiments, in which an initially non-self-associated 4.1R80 isoform became self-associated, suggested that an initially hidden core region was subsequently exposed. This hypothesis was supported by results from pull-down assays, which showed that the core region interacted with the N-terminal end of the FERM (4.1, ezrin, radixin, moesin) domain that is present in 4.1R80 and 4.1R135 isoforms but absent from 4.1R60 isoforms. Consistently, 4.1R80 isoforms bound neither to each other nor to 4.1R60 isoforms. We propose that 4.1R60 isoforms are constitutively self-associated, whereas 4.1R80 and 4.1R135 self-association is prevented by intramolecular interactions.

Intramitochondrial Viruses of Reptilian Cell Origin

1972 ◽  
Vol 30 ◽  
pp. 318-319
Author(s):  
Philip D. Lunger ◽  
H. Fred Clark
Keyword(s):  
Particle Production ◽  
Outer Zone ◽  
Density Variation ◽  
Core Region ◽  
Mitochondrial Membranes ◽  
Virus Particles ◽  
The Core ◽  
Vipera Russelli ◽  
Maturation Stages ◽  
Type Particle

In the course of fine structure studies of spontaneous “C-type” particle production in a viper (Vipera russelli) spleen cell line, designated VSW, virus particles were frequently observed within mitochondria. The latter were usually enlarged or swollen, compared to virus-free mitochondria, and displayed a considerable degree of cristae disorganization.Intramitochondrial viruses measure 90 to 100 mμ in diameter, and consist of a nucleoid or core region of varying density and measuring approximately 45 mμ in diameter. Nucleoid density variation is presumed to reflect varying degrees of condensation, and hence maturation stages. The core region is surrounded by a less-dense outer zone presumably representing viral capsid.Particles are usually situated in peripheral regions of the mitochondrion. In most instances they appear to be lodged between loosely apposed inner and outer mitochondrial membranes.

scholarly journals Lipid binding by the N-terminal motif mediates plasma membrane localization of Bordetella effector protein BteA

2021 ◽  
pp. 100607
Author(s):  
Ivana Malcova ◽  
Ladislav Bumba ◽  
Filip Uljanic ◽  
Darya Kuzmenko ◽  
Jana Nedomova ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Lipid Binding ◽  
Membrane Localization ◽  
Effector Protein ◽  
Plasma Membrane Localization

scholarly journals Influence of Salt on the Self-Organization in Solutions of Star-Shaped Poly-2-alkyl-2-oxazoline and Poly-2-alkyl-2-oxazine on Heating

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1152
Author(s):  
Tatyana Kirila ◽  
Anna Smirnova ◽  
Alla Razina ◽  
Andrey Tenkovtsev ◽  
Alexander Filippov
Keyword(s):  
Phase Separation ◽  
Salt Concentration ◽  
Monomer Unit ◽  
Salt Content ◽  
The Self ◽  
Self Organization ◽  
Phase Separation Temperature ◽  
The Core ◽  
Separation Temperature ◽  
Water Salt

The water–salt solutions of star-shaped six-arm poly-2-alkyl-2-oxazines and poly-2-alkyl-2-oxazolines were studied by light scattering and turbidimetry. The core was hexaaza[26]orthoparacyclophane and the arms were poly-2-ethyl-2-oxazine, poly-2-isopropyl-2-oxazine, poly-2-ethyl-2-oxazoline, and poly-2-isopropyl-2-oxazoline. NaCl and N-methylpyridinium p-toluenesulfonate were used as salts. Their concentration varied from 0–0.154 M. On heating, a phase transition was observed in all studied solutions. It was found that the effect of salt on the thermosensitivity of the investigated stars depends on the structure of the salt and polymer and on the salt content in the solution. The phase separation temperature decreased with an increase in the hydrophobicity of the polymers, which is caused by both a growth of the side radical size and an elongation of the monomer unit. For NaCl solutions, the phase separation temperature monotonically decreased with growth of salt concentration. In solutions with methylpyridinium p-toluenesulfonate, the dependence of the phase separation temperature on the salt concentration was non-monotonic with minimum at salt concentration corresponding to one salt molecule per one arm of a polymer star. Poly-2-alkyl-2-oxazine and poly-2-alkyl-2-oxazoline stars with a hexaaza[26]orthoparacyclophane core are more sensitive to the presence of salt in solution than the similar stars with a calix[n]arene branching center.

scholarly journals On the Nature of R 136, the Central Object of 30 Dor. A Comparison by the Galactic Cluster NGC 3603

1984 ◽  
Vol 108 ◽  
pp. 257-258
Author(s):  
Michael Rosa ◽  
Jorge Melnick ◽  
Preben Grosbol
Keyword(s):  
Core Region ◽  
H Ii Regions ◽  
Central Object ◽  
The Core ◽  
Dominant Component ◽  
Galactic Cluster ◽  
H Ii Region

The massive H II region NGC 3603 is the closest galactic counterpart to the giant LMC nebula 30 Dor. Walborn (1973) first compared the ionizing OB/WR clusters of the two H II regions and suggested that R 136, the unresolved luminous WR + 0 type central object of 30 Dor, might be a multiple system like the core region of NGC 3603. Suggestions that the dominant component of R 136, i.e. R 136A, might be either a single or a very few supermassive and superluminous stars (Schmidt-Kaler and Feitzinger 1982, Savage et al. 1983) have recently been disputed by Moffat and Seggewiss (1983) and Melnick (1983), who have presented spectroscopic and photometric evidence to support the hypothesis of an unresolved cluster of stars. We have extended Walborn's original comparison of the apparent morphology of the two clusters by digital treatment of the images to simulate how the galactic cluster would look like if it were located in the LMC

Reconstruction of the last three millennia South American Monsoon variability over the Amazon basin using speleothem isotope records 

2021 ◽  
Author(s):  
Marcela Eduarda Della Libera de Godoy ◽  
Valdir F. Novello ◽  
Francisco William Cruz
Keyword(s):  
High Resolution ◽  
Amazon Basin ◽  
Rainfall Variability ◽  
Isotope Analysis ◽  
Core Region ◽  
South American ◽  
The South ◽  
Continuous Increase ◽  
South American Monsoon ◽  
The Core

<p>South American Monsoon System (SAMS) and its main feature, the South American Convergence Zone (SACZ) are responsible for the major distribution of moisture in South America. The current work presents a novel high-resolution oxygen isotope record (δ<sup>18</sup>O) based on speleothems from southwest Amazon basin (Brazil), right at SAMS' core region and SACZ onset, where there is still a gap of high resolution paleoclimate records. The novel δ<sup>18</sup>O record presents an average of 3 year-resolution, composed by 1344 stable isotope analysis performed in two speleothems with a well-resolved chronology (37 U/Th ages) with average errors <1%. This work aims to describe the rainfall variability of the core region of the South American monsoon for the last 3k years and to take a broader look at precipitation patterns over Amazon basin. The Rondônia δ18O record shows three main stages throughout this time period. The first is from -1000 to ~400 CE, where it’s in accordance with most of other paleorecords from the Amazon basin. the second segment  is from ~400 to 1200 CE, when there is a continuous increase in the δ18O record until it reaches its highest values around 850 CE during the MCA (800-1200 CE), which is in accordance with western Amazon records, whilst the record in eastern Amazon presents an opposite trend. Thus, a precipitation dipole over Amazon emerges from ~400 CE onwards, majorly triggered by anomalous climate changes such as MCA, where western (eastern) Amazon is drier (wetter). During LIA (1450-1800 CE), on the other hand, Rondônia record presents its lowest values, also agreeing with western records and with records under the influence of SACZ whilst on eastern Amazon a drier period is established. Therefore, with this novel paleoclimate record located at the core region of SAMS, it's possible to evidence the dynamics of the precipitation dipole over the Amazon region, as well as understand the SACZ intensity variations.</p>

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