Membrane–cytoskeleton interactions in cholesterol-dependent domain formation

2015 ◽  
Vol 57 ◽  
pp. 177-187 ◽  
Author(s):  
Jennifer N. Byrum ◽  
William Rodgers
Keyword(s):  
Biological Properties ◽  
Membrane Rafts ◽  
Membrane Domains ◽  
Biological Functions ◽  
Membrane Cytoskeleton ◽  
Heterogeneous Structures ◽  
Integral Role ◽  
Model Cell ◽  
Actomyosin Cytoskeleton ◽  
Dependent Domain

Since the inception of the fluid mosaic model, cell membranes have come to be recognized as heterogeneous structures composed of discrete protein and lipid domains of various dimensions and biological functions. The structural and biological properties of membrane domains are represented by CDM (cholesterol-dependent membrane) domains, frequently referred to as membrane ‘rafts’. Biological functions attributed to CDMs include signal transduction. In T-cells, CDMs function in the regulation of the Src family kinase Lck (p56lck) by sequestering Lck from its activator CD45. Despite evidence of discrete CDM domains with specific functions, the mechanism by which they form and are maintained within a fluid and dynamic lipid bilayer is not completely understood. In the present chapter, we discuss recent advances showing that the actomyosin cytoskeleton has an integral role in the formation of CDM domains. Using Lck as a model, we also discuss recent findings regarding cytoskeleton-dependent CDM domain functions in protein regulation.

scholarly journals Plasma Membrane Protein Nce102 Modulates Morphology and Function of the Yeast Vacuole

Biomolecules ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1476
Author(s):  
Katarina Vaskovicova ◽  
Petra Vesela ◽  
Jakub Zahumensky ◽  
Dagmar Folkova ◽  
Maria Balazova ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Vacuolar Membrane ◽  
Yeast Culture ◽  
Membrane Domains ◽  
Biological Functions ◽  
Plasma Membrane Protein ◽  
Cell Architecture ◽  
And Function

Membrane proteins are targeted not only to specific membranes in the cell architecture, but also to distinct lateral microdomains within individual membranes to properly execute their biological functions. Yeast tetraspan protein Nce102 has been shown to migrate between such microdomains within the plasma membrane in response to an acute drop in sphingolipid levels. Combining microscopy and biochemistry methods, we show that upon gradual ageing of a yeast culture, when sphingolipid demand increases, Nce102 migrates from the plasma membrane to the vacuole. Instead of being targeted for degradation it localizes to V-ATPase-poor, i.e., ergosterol-enriched, domains of the vacuolar membrane, analogous to its plasma membrane localization. We discovered that, together with its homologue Fhn1, Nce102 modulates vacuolar morphology, dynamics, and physiology. Specifically, the fusing of vacuoles, accompanying a switch of fermenting yeast culture to respiration, is retarded in the strain missing both proteins. Furthermore, the absence of either causes an enlargement of ergosterol-rich vacuolar membrane domains, while the vacuoles themselves become smaller. Our results clearly show decreased stability of the V-ATPase in the absence of either Nce102 or Fhn1, a possible result of the disruption of normal microdomain morphology of the vacuolar membrane. Therefore, the functionality of the vacuole as a whole might be compromised in these cells.

scholarly journals Carbohydrate/glycan-binding specificity of legume lectins in respect to their proposed biological functions

2000 ◽  
Vol 43 (4) ◽  
pp. 349-359 ◽  
Author(s):  
Márcio Viana Ramos ◽  
Thalles Barbosa Grangeiro ◽  
Benildo Sousa Cavada ◽  
Iain Shepherd ◽  
Roberval Oliveira de Melo Lopes ◽  
...  
Keyword(s):  
Molecular Basis ◽  
Binding Specificity ◽  
Biological Properties ◽  
The Other ◽  
Biological Functions ◽  
Main Hypothesis ◽  
Physiological Functions ◽  
Legume Plants ◽  
Legume Lectins ◽  
Structural Aspects

The lectins, proteins which specifically recognize carbohydrate moieties, have been extensively studied in many biochemical and structural aspects in order to establish the molecular basis of this non-catalytic event. On the other hand, their clinical and agricultural potentials have been growing fast. Although lectins, mainly those from legume plants, had been investigated for biological properties, studies about the physiological functions of lectins are scarce in literature. Therefore, despite the accumulated data on lectins (as proteins), the role played by these signalizing molecules is poorly discussed. In the light of our accumulated results on legume lectins, specially those obtained from plants belonging to the Diocleinae sub-tribe and available data in literature, we discuss here the main hypothesis of their functions according to their carbohydrate/glycan-binding specificity.

scholarly journals DISRUPTION OF PROTEIN COMPLEXES

2013 ◽  
Vol 11 (03) ◽  
pp. 1341008 ◽  
Author(s):  
GOLNAZ TAHERI ◽  
MAHNAZ HABIBI ◽  
LIMSOON WONG ◽  
CHANGIZ ESLAHCHI
Keyword(s):  
Protein Complexes ◽  
Biological Properties ◽  
Alternative Methods ◽  
Biological Processes ◽  
Biological Functions ◽  
Yeast Protein ◽  
Minimal Set ◽  
Connection Degree ◽  
Minimum Number ◽  
Molecular Machinery

Protein complexes are a cornerstone of many biological processes and, together, they form various types of molecular machinery that perform a vast array of biological functions. Different complexes perform different functions and, the same complex can perform very different functions that depend on a variety of factors. Thus disruption of protein complexes can be lethal to an organism. It is interesting to identify a minimal set of proteins whose removal would lead to a massive disruption of protein complexes and, to understand the biological properties of these proteins. A method is presented for identifying a minimum number of proteins from a given set of complexes so that a maximum number of these complexes are disrupted when these proteins are removed. The method is based on spectral bipartitioning. This method is applied to yeast protein complexes. The identified proteins participate in a large number of biological processes and functional modules. A large proportion of them are essential proteins. Moreover, removing these identified proteins causes a large number of the yeast protein complexes to break into two fragments of nearly equal size, which minimizes the chance of either fragment being functional. The method is also superior in these aspects to alternative methods based on proteins with high connection degree, proteins whose neighbors have high average degree, and proteins that connect to lots of proteins of high connection degree. Our spectral bipartitioning method is able to efficiently identify a biologically meaningful minimal set of proteins whose removal causes a massive disruption of protein complexes in an organism.

scholarly journals Emerging roles of RNA methylation in gastrointestinal cancers

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Shanshan Xie ◽  
Wenwen Chen ◽  
Kanghua Chen ◽  
Yongxia Chang ◽  
Feng Yang ◽  
...  
Keyword(s):  
Cancer Progression ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Human Cancer ◽  
Biological Properties ◽  
Cancer Development ◽  
Biological Functions ◽  
Gastrointestinal Cancers ◽  
Rna Methylation ◽  
Fundamental Process

AbstractRNA methylation has emerged as a fundamental process in epigenetic regulation. Accumulating evidences indicate that RNA methylation is essential for many biological functions, and its dysregulation is associated with human cancer progression, particularly in gastrointestinal cancers. RNA methylation has a variety of biological properties, including N6-methyladenosine (m6A), 2-O-dimethyladenosine (m6Am), N1-methyladenosine (m1A), 5-methylcytosine (m5C) and 7-methyl guanosine (m7G). Dynamic and reversible methylation on RNA is mediated by RNA modifying proteins called “writers” (methyltransferases) and “erasers” (demethylases). “Readers” (modified RNA binding proteins) recognize and bind to RNA methylation sites, which influence the splicing, stability or translation of modified RNAs. Herein, we summarize the biological functions and mechanisms of these well-known RNA methylations, especially focusing on the roles of m6A in gastrointestinal cancer development.

scholarly journals PA28γ: New Insights on an Ancient Proteasome Activator

Biomolecules ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 228 ◽  
Author(s):  
Paolo Cascio
Keyword(s):  
Molecular Mechanisms ◽  
Regulatory Protein ◽  
Biological Properties ◽  
Biochemical Properties ◽  
20S Proteasome ◽  
Biological Functions ◽  
Cellular Processes ◽  
Degradation Rates ◽  
The Common ◽  
Proteasome Regulators

PA28 (also known as 11S, REG or PSME) is a family of proteasome regulators whose members are widely present in many of the eukaryotic supergroups. In jawed vertebrates they are represented by three paralogs, PA28α, PA28β, and PA28γ, which assemble as heptameric hetero (PA28αβ) or homo (PA28γ) rings on one or both extremities of the 20S proteasome cylindrical structure. While they share high sequence and structural similarities, the three isoforms significantly differ in terms of their biochemical and biological properties. In fact, PA28α and PA28β seem to have appeared more recently and to have evolved very rapidly to perform new functions that are specifically aimed at optimizing the process of MHC class I antigen presentation. In line with this, PA28αβ favors release of peptide products by proteasomes and is particularly suited to support adaptive immune responses without, however, affecting hydrolysis rates of protein substrates. On the contrary, PA28γ seems to be a slow-evolving gene that is most similar to the common ancestor of the PA28 activators family, and very likely retains its original functions. Notably, PA28γ has a prevalent nuclear localization and is involved in the regulation of several essential cellular processes including cell growth and proliferation, apoptosis, chromatin structure and organization, and response to DNA damage. In striking contrast with the activity of PA28αβ, most of these diverse biological functions of PA28γ seem to depend on its ability to markedly enhance degradation rates of regulatory protein by 20S proteasome. The present review will focus on the molecular mechanisms and biochemical properties of PA28γ, which are likely to account for its various and complex biological functions and highlight the common features with the PA28αβ paralog.

scholarly journals Function of membrane domains in Rho-Of-Plant signaling

2021 ◽  
Author(s):  
Marija Smokvarska ◽  
Yvon Jaillais ◽  
Alexandre Martinière
Keyword(s):  
Current Knowledge ◽  
Biological Properties ◽  
Vesicular Trafficking ◽  
Membrane Domains ◽  
Plant Signaling ◽  
Guanosine Triphosphate ◽  
Long Time ◽  
Signal Specificity ◽  
Cytoskeleton Dynamics ◽  
Crowded Environment

Abstract In a crowded environment, establishing interactions between different molecular partners can take a long time. Biological membranes have solved this issue, as they simultaneously are fluid and possess compartmentalized domains. This nanoscale organization of the membrane is often based on weak, local and multivalent interactions between lipids and proteins. However, from local interactions at the nanoscale, different functional properties emerge at the higher scale, and these are critical to regulate and integrate cellular signaling. Rho of Plant (ROP) proteins are small guanosine triphosphate hydrolase enzymes (GTPases) involved in hormonal, biotic, and abiotic signaling, as well as fundamental cell biological properties such as polarity, vesicular trafficking and cytoskeleton dynamics. Association with the membrane is essential for ROP function, as well as their precise targeting within micrometer-sized polar domains (i.e. microdomains) and nanometer-sized clusters (i.e. nanodomains). Here, we review our current knowledge about the formation and the maintenance of the ROP domains in membranes. Furthermore, we propose a model for ROP membrane targeting and discuss how the nano-scale organization of ROPs in membranes could determine signaling parameters like signal specificity, amplification and integration.

scholarly journals Secondary metabolites in plants: main classes, phytochemical analysis and pharmacological activities

Bionatura ◽  
2019 ◽  
Vol 4 (4) ◽  
pp. 1000-1009
Author(s):  
Irina Francesca González Mera ◽  
Daniela Estefanía González Falconí ◽  
Vivian Morera Córdova
Keyword(s):  
Secondary Metabolites ◽  
Secondary Metabolism ◽  
Chemical Compounds ◽  
Biological Properties ◽  
Phytochemical Analysis ◽  
Phytochemical Screening ◽  
Biological Functions ◽  
Pharmacological Activities

Plants are an essential source of chemical compounds with different biological properties that man can use to his advantage. These substances are mainly produced as a result of chemical conversions of secondary metabolism. This article reviews the main classes of secondary metabolites that synthesize plants as well as their characteristics and their biological functions. Examples are provided for each of the classes. Emphasis is placed on the methods of extracting secondary metabolites and phytochemical screening, as well as on the main pharmacological activities described for the MS.

Targeting Breast Cancer Stem Cells: A Methodological Perspective

2019 ◽  
Vol 14 (5) ◽  
pp. 389-397
Author(s):  
Marco A. Velasco-Velázquez ◽  
Inés Velázquez-Quesada ◽  
Luz X. Vásquez-Bochm ◽  
Sonia M. Pérez-Tapia
Keyword(s):  
Breast Cancer ◽  
Stem Cells ◽  
Cancer Stem Cells ◽  
Experimental Methods ◽  
Biological Properties ◽  
Clear Understanding ◽  
Breast Cancer Stem Cells ◽  
Biological Functions ◽  
Breast Cscs ◽  
Preclinical Evaluation

Cancer Stem Cells (CSCs) constitute a subpopulation at the top of the tumor cell hierarchy that contributes to tumor heterogeneity and is uniquely capable of seeding new tumors. Because of their biological properties, CSCs have been pointed out as therapeutic targets for the development of new therapies against breast cancer. The identification of drugs that selectively target breast CSCs requires a clear understanding of their biological functions and the experimental methods to evaluate such hallmarks. Herein, we review the methods to study breast CSCs properties and discuss their value in the preclinical evaluation of CSC-targeting drugs.

Relationship between Kir2.1/Kir2.3 activity and their distributions between cholesterol-rich and cholesterol-poor membrane domains

2007 ◽  
Vol 293 (1) ◽  
pp. C440-C450 ◽  
Author(s):  
Saloni Tikku ◽  
Yulia Epshtein ◽  
Heidi Collins ◽  
Alexander J. Travis ◽  
George H. Rothblat ◽  
...  
Keyword(s):  
Opposite Effect ◽  
Membrane Rafts ◽  
Cholesterol Depletion ◽  
Membrane Domains ◽  
Double Peak ◽  
Cellular Cholesterol ◽  
Different Types ◽  
Lipid Environment ◽  
Kinetics Of

Our earlier studies have shown that Kir2.x channels are suppressed by an increase in the level of cellular cholesterol, whereas cholesterol depletion enhances the activity of the channels. In this study, we show that Kir2.1 and Kir2.3 channels have double-peak distributions between cholesterol-rich (raft) and cholesterol-poor (non-raft) membrane fractions, indicating that the channels exist in two different types of lipid environment. We also show that whereas methyl-β-cyclodextrin-induced cholesterol depletion removes cholesterol from both raft and non-raft membrane fractions, cholesterol enrichment results in cholesterol increase exclusively in the raft fractions. Kinetics of both depletion-induced Kir2.1 enhancement and enrichment-induced Kir2.1 suppression correlate with the changes in the level of raft cholesterol. Furthermore, we show not only that cholesterol depletion shifts the distribution of the channels from cholesterol-rich to cholesterol-poor membrane fractions but also that cholesterol enrichment has the opposite effect. These observations suggest that change in the level of raft cholesterol alone is sufficient to suppress Kir2 activity and to facilitate partitioning of the channels to cholesterol-rich domains. Therefore, we suggest that partitioning to membrane rafts plays an important role in the sensitivity of Kir2 channels to cholesterol.

scholarly journals Lactoferrin: a review

2008 ◽  
Vol 53 (No. 9) ◽  
pp. 457-468 ◽  
Author(s):  
L. Adlerova ◽  
A. Bartoskova ◽  
M. Faldyna
Keyword(s):  
Biological Properties ◽  
Exocrine Glands ◽  
Iron Binding ◽  
Biological Functions ◽  
Binding Ability ◽  
Antiparasitic Activity ◽  
Cell Proliferation And Differentiation ◽  
Proliferation And Differentiation ◽  
Specific Granules ◽  
The Relationship

This review discusses the biological properties of the glycoprotein lactoferrin. Lactoferrin has been identified in secretions from exocrine glands and in specific granules of neutrophils. After degranulation, neutrophils become the main source of lactoferrin in blood plasma. Lactoferrin possesses various biological functions, including roles in iron metabolism, cell proliferation and differentiation, and antibacterial, antiviral, and antiparasitic activity. Many of these functions do not appear to be connected with its iron binding ability. Of late, lactoferrin concentrations have been measured mostly in humans but also in some other species. However, the relationship between its concentration and physiological or pathological effects on body functions is not yet well characterised.

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