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.

scholarly journals Characterization of rifampicin-resistant Mycobacterium tuberculosis in Taiwan

2003 ◽  
Vol 52 (3) ◽  
pp. 239-245 ◽  
Author(s):  
Hsing-Yu Hwang ◽  
Chung-Yu Chang ◽  
Lin-Li Chang ◽  
Shui-Feng Chang ◽  
Ya-Hui Chang ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Core Region ◽  
Banding Patterns ◽  
The Core ◽  
Resistant Tuberculosis ◽  
Proportion Method ◽  
The Mean ◽  
Novel Alleles ◽  
The Relationship

Sixty-three rifampicin-resistant (Rifr) isolates of Mycobacterium tuberculosis from Kaohsiung, Taiwan, were analysed for mutations in the core region (69 bp, codons 511–533) of the rpoB gene. Some 84.1 % (53/63) of the resistant isolates showed mutations in this region, especially in codons 531 (41.5 %), 526 (18.9 %), 516 (15.1 %) and 533 (7.5 %). Five novel alleles of a total of 16 different types of mutations were identified in Rifr isolates. Ten Rifr isolates (15.9 %) exhibited no mutations in the core region of rpoB. Also, they did not show mutations in another 365 bp fragment (codons 99–220) of rpoB. The agar proportion method was used to determine the relationship between the degree of rifampicin resistance and alterations in the core region of rpoB. The results revealed that the mean MIC was 92.38 μg ml−1 for the 53 isolates with a mutation in the core region, whereas the mean MIC of the other 10 isolates without mutations was only 24.8 μg ml−1. This indicates that the isolates with mutations in the core region had higher levels of resistance than those without mutations in this region. IS6110 restriction fragment length polymorphism (RFLP) was used for typing of 55 Rifr M. tuberculosis isolates. Isolates contained two to 19 copies of IS6110, with sizes ranging from 600 to 16 000 bp. The majority (85 %) contained six to 16 copies. No strains lacking IS6110 were found. A total of 54 of 55 RFLP types were defined at the 90 % similarity level. The observation of varied IS6110-associated banding patterns indicates that an outbreak of drug-resistant tuberculosis did not occur in this area.

scholarly journals Characterization of TSET, an ancient and widespread membrane trafficking complex

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Jennifer Hirst ◽  
Alexander Schlacht ◽  
John P Norcott ◽  
David Traynor ◽  
Gareth Bloomfield ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Trafficking ◽  
Scaffolding Proteins ◽  
Eukaryotic Evolution ◽  
Bioinformatics Tool ◽  
Membrane Turnover ◽  
Evolutionary Path ◽  
The Core ◽  
Eukaryotic Supergroup

The heterotetrameric AP and F-COPI complexes help to define the cellular map of modern eukaryotes. To search for related machinery, we developed a structure-based bioinformatics tool, and identified the core subunits of TSET, a 'missing link' between the APs and COPI. Studies in Dictyostelium indicate that TSET is a heterohexamer, with two associated scaffolding proteins. TSET is non-essential in Dictyostelium, but may act in plasma membrane turnover, and is essentially identical to the recently described TPLATE complex, TPC. However, whereas TPC was reported to be plant-specific, we can identify a full or partial complex in every eukaryotic supergroup. An evolutionary path can be deduced from the earliest origins of the heterotetramer/scaffold coat to its multiple manifestations in modern organisms, including the mammalian muniscins, descendants of the TSET medium subunits. Thus, we have uncovered the machinery for an ancient and widespread pathway, which provides new insights into early eukaryotic evolution.

scholarly journals Membrane protein interactions in sickle red blood cells: evidence of abnormal protein 3 function

Blood ◽  
1995 ◽  
Vol 86 (5) ◽  
pp. 1992-1998 ◽  
Author(s):  
OS Platt ◽  
JF Falcone
Keyword(s):  
Membrane Proteins ◽  
Red Blood Cells ◽  
Protein Interactions ◽  
Blood Cells ◽  
Binding Domain ◽  
Protein 4.1 ◽  
Functional Defect ◽  
Sickle Red Blood Cells ◽  
Self Association ◽  
Actin Protein

The pattern of membrane abnormalities in sickle red blood cells suggests that sickle hemoglobin damages membrane proteins. We have previously shown a functional defect in sickle ankyrin, poor spectrin- binding ability. Here we examine the other major binding interactions of sickle membrane proteins including spectrin self-association, binding of ankyrin and protein 4.1 to protein 3, and the formation of the spectrin-actin-protein 4.1 complex. We found that sickle spectrin was normal in self-association and ability to participate in the spectrin-actin-protein 4.1 complex. Sickle protein 4.1 bound normally to protein 3 and formed normal complexes with actin and spectrin, even when sickle spectrin was used. The only major abnormality we found was a reduced ability of sickle protein 3 to bind ankyrin. This functional defect could not be explained experimentally on the basis of cysteine modification or enhanced tyrosine phosphorylation. We conclude that damage of sickle membrane proteins is not a diffuse scattershot process, but is largely confined to regions near membrane-associated hemoglobin, the spectrin-binding domain of ankyrin and the ankyrin- binding domain of protein 3. The mechanism and consequences of this damage continues to be investigated.

scholarly journals Structural and Computational Characterization of Disease-Related Mutations Involved in Protein-Protein Interfaces

2019 ◽  
Vol 20 (7) ◽  
pp. 1583 ◽  
Author(s):  
Dàmaris Navío ◽  
Mireia Rosell ◽  
Josu Aguirre ◽  
Xavier de la Cruz ◽  
Juan Fernández-Recio
Keyword(s):  
Protein Interactions ◽  
Computational Analysis ◽  
Molecular Level ◽  
Binding Free Energy ◽  
Evolutionary Conservation ◽  
Core Region ◽  
Protein Protein Interactions ◽  
The Core ◽  
Protein Interfaces

One of the known potential effects of disease-causing amino acid substitutions in proteins is to modulate protein-protein interactions (PPIs). To interpret such variants at the molecular level and to obtain useful information for prediction purposes, it is important to determine whether they are located at protein-protein interfaces, which are composed of two main regions, core and rim, with different evolutionary conservation and physicochemical properties. Here we have performed a structural, energetics and computational analysis of interactions between proteins hosting mutations related to diseases detected in newborn screening. Interface residues were classified as core or rim, showing that the core residues contribute the most to the binding free energy of the PPI. Disease-causing variants are more likely to occur at the interface core region rather than at the interface rim (p < 0.0001). In contrast, neutral variants are more often found at the interface rim or at the non-interacting surface rather than at the interface core region. We also found that arginine, tryptophan, and tyrosine are over-represented among mutated residues leading to disease. These results can enhance our understanding of disease at molecular level and thus contribute towards personalized medicine by helping clinicians to provide adequate diagnosis and treatments.

Structural characterization of the core region from the lipopolysaccharide of the haloalkaliphilic bacterium Halomonas alkaliantarctica strain CRSS

2010 ◽  
Vol 8 (23) ◽  
pp. 5404 ◽  
Author(s):  
Giuseppina Pieretti ◽  
Sara Carillo ◽  
Barbara Nicolaus ◽  
Annarita Poli ◽  
Rosa Lanzetta ◽  
...  
Keyword(s):  
Structural Characterization ◽  
Core Region ◽  
The Core

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.

A constitutive region is responsible for nuclear targeting of 4.1R: modulation by alternative sequences results in differential intracellular localization

2000 ◽  
Vol 113 (13) ◽  
pp. 2485-2495 ◽  
Author(s):  
C.M. Luque ◽  
I. Correas
Keyword(s):  
Translation Initiation ◽  
Intracellular Localization ◽  
Inhibitory Effect ◽  
Initiation Site ◽  
Core Region ◽  
Cell Protein ◽  
Translation Initiation Site ◽  
Nuclear Targeting ◽  
The Core ◽  
Protein 4.1R

Red blood cell protein 4.1, 4.1R, is an extreme variation on the theme of isoform multiplicity. The diverse 4.1R isoforms, mainly generated by alternative pre-mRNA splicing, are localized at different intracellular sites, including the nucleus. To characterize nonerythroid 4.1 proteins lacking the most upstream translation initiation site, analyze their intracellular localization and define specific domains involved in differential intracellular targeting of 4.1R, we cloned 4.1 cDNAs lacking that translation initiation site. Seven different 4.1R cDNAs were isolated. Four of these encoded 4.1R proteins localized predominantly to the nucleus and the other three localized to the cytoplasm. Three of the nuclear 4.1R isoforms did not contain the nuclear localization signal previously identified in the alternative exon 16. A comparative analysis of the exon composition of the naturally occurring 4.1R cDNAs cloned and of appropriate composite cDNA constructs, with the subcellular distribution of their respective products, demonstrated that a region encoded by constitutive exons, which is therefore common to all 4.1R isoforms and has been termed ‘core region’, had the capacity of localizing to the nucleus. This region was able to confer nuclear targeting to a cytosolic reporter. In protein 4.1R isoforms, the nuclear targeting of the core region is modulated by the expression of alternative exons. Thus, exon 5-encoded sequences eclipsed nuclear entry of the core region, resulting in 4.1R isoforms that predominantly distributed to the cytoplasm. Exon 5 was also able to confer cytoplasmic localization to a nuclear reporter. In protein 4.1R isoforms, when exons 5 and 16 were both expressed the nuclear targeting effect of exon 16 was dominant to the inhibitory effect observed by the expression of exon 5, yielding proteins that predominantly localized to the nucleus. Taken together, these results indicate that all 4.1R molecules contain a conserved region that is sufficient to target the protein to the nucleus, but that specific exon-encoded sequences modulate this capacity by acting in a hierarchical order.

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