Chemical guidance of Onchocerca lienalis microfilariae to the thorax of Simulium vittatum

Parasitology ◽  
1995 ◽  
Vol 110 (3) ◽  
pp. 329-337 ◽  
Author(s):  
T. Lehmann ◽  
S. M. Cupp ◽  
W. E. Cupp
Keyword(s):  
Protein S ◽  
Chemical Cue ◽  
Simulium Vittatum ◽  
Large Molecular Weight ◽  
Tissue Factors ◽  
Weight Protein ◽  
Tissue Size ◽  
Thoracic And Abdominal ◽  
Complete Precipitation

SUMMARYThe behavioural responses of Onchocerca lienalis microfilariae (mf) to tissue factors of the surrogate black fly host, Simulium vittatum, were studied using a novel in vitro bioassay. Mf accumulated towards thoracic tissues to a density 4 times higher than towards abdominal tissues, despite the larger surface area and volume of abdominal tissues. Mf migrated toward thoracic tissues regardless of whether or not contact with thoracic tissues was possible. Therefore, mf directed themselves toward the thorax rather than arresting their movement after they make contact with thoracic tissues. Chemical cue(s) provided a principal guidance for mf to locate thoracic tissues. Mf lost their ability to differentiate thoracic and abdominal tissues following addition of thoracic attractant(s) to excised abdomens and reversed their differential response when excised thoraces were depleted of chemical cue(s). Mf did not respond to salivary gland product, but to other thoracic factor(s). Intact thorax that was connected to 1–2 abdominal segments attracted considerably less mf than excised thorax. However, intact thorax attracted more mf than excised abdomen. Abdominal tissue size did not affect thorax attractiveness. Involvement of a large molecular weight protein(s) was suggested by the high attractiveness of the 100 kDa Centricon concentrator retentate and complete precipitation of attractant(s) by ethanol.

scholarly journals The N-Terminus ofDictyosteliumScar Interacts with Abi and HSPC300 and Is Essential for Proper Regulation and Function

2007 ◽  
Vol 18 (5) ◽  
pp. 1609-1620 ◽  
Author(s):  
Diana Caracino ◽  
Cheryl Jones ◽  
Mark Compton ◽  
Charles L. Saxe
Keyword(s):  
Actin Polymerization ◽  
Terminal Region ◽  
Wild Type ◽  
Large Molecular Weight ◽  
Weight Protein ◽  
And Function ◽  
Necessary And Sufficient

Scar/WAVE proteins, members of the conserved Wiskott-Aldrich syndrome (WAS) family, promote actin polymerization by activating the Arp2/3 complex. A number of proteins, including a complex containing Nap1, PIR121, Abi1/2, and HSPC300, interact with Scar/WAVE, though the role of this complex in regulating Scar function remains unclear. Here we identify a short N-terminal region of Dictyostelium Scar that is necessary and sufficient for interaction with HSPC300 and Abi in vitro. Cells expressing Scar lacking this N-terminal region show abnormalities in F-actin distribution, cell morphology, movement, and cytokinesis. This is true even in the presence of wild-type Scar. The data suggest that the first 96 amino acids of Scar are necessary for participation in a large-molecular-weight protein complex, and that this Scar-containing complex is responsible for the proper localization and regulation of Scar. The presence of mis-regulated or unregulated Scar has significant deleterious effects on cells and may explain the need to keep Scar activity tightly controlled in vivo either by assembly in a complex or by rapid degradation.

scholarly journals In vitro and computational studies of transdermal perfusion of nanoformulations containing a large molecular weight protein

2013 ◽  
Vol 108 ◽  
pp. 271-278 ◽  
Author(s):  
Madalena Martins ◽  
Nuno G. Azoia ◽  
Artur Ribeiro ◽  
Ulyana Shimanovich ◽  
Carla Silva ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Computational Studies ◽  
Molecular Weight Protein ◽  
Large Molecular Weight ◽  
Weight Protein

Activated Protein C Increases Fibrin Clot Lysis by Neutralization of Plasminogen Activator Inhibitor No Evidence for a Cofactor Role of Protein S

1988 ◽  
Vol 60 (02) ◽  
pp. 328-333 ◽  
Author(s):  
N J de Fouw ◽  
Y F de Jong ◽  
F Haverkate ◽  
R M Bertina
Keyword(s):  
Plasminogen Activator ◽  
Protein C ◽  
Blood Platelets ◽  
Plasminogen Activator Inhibitor ◽  
Protein S ◽  
Tissue Type ◽  
Clot Lysis ◽  
Activator Inhibitor ◽  
Pai 1

summaryThe effect of purified human activated protein G (APC) on fibrinolysis was studied using a clot iysis system consisting of purified glu-plasminogen, tissue-type plasminogen activator, plasminogen activator inhibitor (released from endothelial cells or blood platelets), fibrinogen, 125T-fibrinogen and thrombin. All proteins were of human origin.In this system APC could increase fibrinolysis in a dose dependent way, without affecting fibrin formation or fibrin crosslinking. However, this profibrinolytic effect of APC could only be observed when plasminogen activator inhibitor (PAI-l) was present. The effect of APC was completely quenched by pretreatment of APC with anti-protein C IgG or di-isopropylfluorophosphate. Addition of the cofactors of APC:protein S, Ca2+-ions and phospholipid-alone or in combination did not enhance the profibrinolytic effect of APC. These observations indicate that human APC can accelerate in vitro clot lysis by the inactivation of PAI-1 activity. However, the neutralization of PAI-1 by APC is independent of the presence or absence of protein S, phospholipid and Ca2+-ions.

The Anticoagulant Properties of a Modified Form of Protein S

1988 ◽  
Vol 60 (02) ◽  
pp. 298-304 ◽  
Author(s):  
C A Mitchell ◽  
S M Kelemen ◽  
H H Salem
Keyword(s):  
Monoclonal Antibody ◽  
Anticoagulant Activity ◽  
Activated Protein C ◽  
Factor Xa ◽  
Protein S ◽  
Human Neutrophil Elastase ◽  
Factor X ◽  
Sds Page

SummaryProtein S (PS) is a vitamin K-dependent anticoagulant that acts as a cofactor to activated protein C (APC). To date PS has not been shown to possess anticoagulant activity in the absence of APC.In this study, we have developed monoclonal antibody to protein S and used to purify the protein to homogeneity from plasma. Affinity purified protein S (PSM), although identical to the conventionally purified protein as judged by SDS-PAGE, had significant anticoagulant activity in the absence of APC when measured in a factor Xa recalcification time. Using SDS-PAGE we have demonstrated that prothrombin cleavage by factor X awas inhibited in the presence of PSM. Kinetic analysis of the reaction revealed that PSM competitively inhibited factor X amediated cleavage of prothrombin. PS preincubated with the monoclonal antibody, acquired similar anticoagulant properties. These results suggest that the interaction of the monoclonal antibody with PS results in an alteration in the protein exposing sites that mediate the observed anticoagulant effect. Support that the protein was altered was derived from the observation that PSM was eight fold more sensitive to cleavage by thrombin and human neutrophil elastase than conventionally purified protein S.These observations suggest that PS can be modified in vitro to a protein with APC-independent anticoagulant activity and raise the possibility that a similar alteration could occur in vivo through the binding protein S to a cellular or plasma protein.

Observations on the in vitro Effects of Chylomicra, Low-Density Lipoproteins and Phospholipids on Human Plasma Euglobulin Lysis

1963 ◽  
Vol 09 (01) ◽  
pp. 164-174 ◽  
Author(s):  
Albert R Pappenhagen ◽  
J. L Koppel ◽  
John H Olwin
Keyword(s):  
Human Plasma ◽  
Phosphatidyl Ethanolamine ◽  
Phosphatidyl Inositol ◽  
Plasma Lipoproteins ◽  
Low Density ◽  
Inhibitory Effects ◽  
Soybean Phospholipids ◽  
In Vitro Effects ◽  
Complete Precipitation

SummaryData have been presented on the in vitro effects of human chylomicra, low-density human plasma lipoproteins, and partially purified preparations of various phospholipids on human plasma euglobulin lysis. Euglobulin lysis was found to be accelerated by preparations of mixed soybean phospholipids (aso-lectin), cephalin, phosphatidyl inositol, phophatidyl serine and phosphatidyl ethanolamine. In contrast, it was found to be inhibited by preparations of human chylomicra, low-density human plasma liproproteins and lecithin. Inhibition of euglobulin lysis produced by any of these three agents could be diminished or completely overcome by the simultaneous presence of suitable levels of any one of the accelerating agents. In all cases studied, both inhibitory and accelerating effects were observed to be concentration-dependent. Evidence has been obtained to suggest that in the case of the accelerating agents the observed increased rate of euglobulin lysis is not a direct effect on lysis itself, but rather is due to more complete precipitation of plasminogen in the presence of these substances. On the other hand, it appears that the inhibitory effects observed are not related to the extent of plasminogen precipitation, but are actually true inhibitions of euglobulin lysis. The possible clinical significance of some of these observations has been briefly discussed.

scholarly journals The two redox states of the human NEET proteins’ [2Fe–2S] clusters

2021 ◽  
Vol 26 (7) ◽  
pp. 763-774
Author(s):  
Ke Zuo ◽  
Henri-Baptiste Marjault ◽  
Kara L. Bren ◽  
Giulia Rossetti ◽  
Rachel Nechushtai ◽  
...  
Keyword(s):  
Protein S ◽  
Spectroscopic Studies ◽  
Reduced Form ◽  
Rieske Protein ◽  
Kinetic Measurements ◽  
Redox States ◽  
Extra Electron ◽  
Dynamics Simulations ◽  
Reduced State

AbstractThe NEET proteins constitute a unique class of [2Fe–2S] proteins. The metal ions bind to three cysteines and one histidine. The proteins’ clusters exist in two redox states; the oxidized protein (containing two FeIII ions) can transfer the cluster to apo-acceptor protein(s), while the reduced form (containing one ferrous ion) remains bound to the protein frame. Here, we perform in silico and in vitro studies on human NEET proteins in both reduced and oxidized forms. Quantum chemical calculations on all available human NEET proteins structures suggest that reducing the cluster weakens the Fe–NHis and Fe–SCys bonds, similar to what is seen in other Fe–S proteins (e.g., ferredoxin and Rieske protein). We further show that the extra electron in the [2Fe–2S]+ clusters of one of the NEET proteins (mNT) is localized on the His-bound iron ion, consistently with our previous spectroscopic studies. Kinetic measurements demonstrate that the mNT [2Fe–2S]+ is released only by an increase in temperature. Thus, the reduced state of human NEET proteins [2Fe–2S] cluster is kinetically inert. This previously unrecognized kinetic inertness of the reduced state, along with the reactivity of the oxidized state, is unique across all [2Fe–2S] proteins. Finally, using a coevolutionary analysis, along with molecular dynamics simulations, we provide insight on the observed allostery between the loop L2 and the cluster region. Specifically, we show that W75, R76, K78, K79, F82 and G85 in the latter region share similar allosteric characteristics in both redox states. Graphic abstract

Semi-purification procedures of prions from a prion-infected brain using sucrose has no influence on the nonenzymatic glycation of the disease-associated prion isoform

2016 ◽  
Vol 397 (2) ◽  
pp. 125-133 ◽  
Author(s):  
Yeong-Gon Choi ◽  
Jae-Il Kim ◽  
Eun-Kyoung Choi ◽  
Richard I. Carp ◽  
Yong-Sun Kim
Keyword(s):  
Colloidal Silica ◽  
Protein S ◽  
Core Region ◽  
Advanced Glycation ◽  
Nonenzymatic Glycation ◽  
Pellet Fraction ◽  
Sucrose Cushion ◽  
Advanced Glycation End Product ◽  
Modified Polymer

Abstract Previous studies have shown that the Nε-carboxymethyl group is linked to not only one or more N-terminal Lys residues but also to one or more Lys residues of the protease-resistant core region of the pathogenic prion isoform (PrPSc) in prion-infected brains. Using an anti-advanced glycation end product (AGE) antibody, we detected nonenzymatically glycated PrPSc (AGE-PrPSc) in prion-infected brains following concentration by a series of ultracentrifugation steps with a sucrose cushion. In the present study, the levels of in vitro nonenzymatic glycation of PrPSc using sucrose were investigated to determine whether sucrose cushion can artificially and nonenzymatically induce in vitro glycation during ultracentrifugation. The first insoluble pellet fraction following the first ultracentrifugation (PU1st) collected from 263K scrapie-infected brains was incubated with sucrose, glucose or colloidal silica coated with polyvinylpyrrolidone (percoll). None of the compounds in vitro resulted in AGE-PrPSc. Nonetheless, glucose and percoll produced AGEs in vitro from other proteins within PU1st of the infected brains. This reaction could lead to the AGE-modified polymer(s) of nonenzymatic glycation-prone protein(s). This study showed that PrPSc is not nonenzymatically glycated in vitro with sucrose, glucose or percoll and that AGE-modified PrPSc can be isolated and enriched from prion-infected brains.

scholarly journals Differential regulation of two distinct families of glucose transporter genes in Trypanosoma brucei.

1993 ◽  
Vol 13 (2) ◽  
pp. 1146-1154 ◽  
Author(s):  
F Bringaud ◽  
T Baltz
Keyword(s):  
Trypanosoma Brucei ◽  
Xenopus Oocytes ◽  
Glucose Transporter ◽  
Protein S ◽  
Life Cycle Stage ◽  
Good Target ◽  
Hexose Transporters ◽  
Moderate Sensitivity ◽  
Mrna Analysis

A tandemly arranged multigene family encoding putative hexose transporters in Trypanosoma brucei has been characterized. It is composed of two 80% homologous groups of genes called THT1 (six copies) and THT2 (five copies). When Xenopus oocytes are microinjected with in vitro-transcribed RNA from a THT1 gene, they express a glucose transporter with properties similar to those of the trypanosome bloodstream-form protein(s). This THT1-encoded transport system for glucose differs from the human erythrocyte-type glucose transporter by its moderate sensitivity to cytochalasin B and its capacity to transport D-fructose. These properties suggest that the trypanosomal transporter may be a good target for antitrypanosomal drugs. mRNA analysis revealed that expression of these genes was life cycle stage dependent. Bloodstream forms express 40-fold more THT1 than THT2. In contrast, procyclic trypanosomes express no detectable THT1 but demonstrate glucose-dependent expression of THT2.

scholarly journals An engineered decoy receptor for SARS-CoV-2 broadly binds protein S sequence variants

2021 ◽  
Vol 7 (8) ◽  
pp. eabf1738 ◽  
Author(s):  
Kui K. Chan ◽  
Timothy J. C. Tan ◽  
Krishna K. Narayanan ◽  
Erik Procko
Keyword(s):  
In Vitro Selection ◽  
Protein S ◽  
Saturation Mutagenesis ◽  
Wild Type ◽  
Host Cell Membrane ◽  
Decoy Receptor ◽  
Decoy Receptors ◽  
Binding Surface ◽  
Type Receptor

The spike S of SARS-CoV-2 recognizes ACE2 on the host cell membrane to initiate entry. Soluble decoy receptors, in which the ACE2 ectodomain is engineered to block S with high affinity, potently neutralize infection and, because of close similarity with the natural receptor, hold out the promise of being broadly active against virus variants without opportunity for escape. Here, we directly test this hypothesis. We find that an engineered decoy receptor, sACE22.v2.4, tightly binds S of SARS-associated viruses from humans and bats, despite the ACE2-binding surface being a region of high diversity. Saturation mutagenesis of the receptor-binding domain followed by in vitro selection, with wild-type ACE2 and the engineered decoy competing for binding sites, failed to find S mutants that discriminate in favor of the wild-type receptor. We conclude that resistance to engineered decoys will be rare and that decoys may be active against future outbreaks of SARS-associated betacoronaviruses.

Protein synthesis is required for rapid degradation of tubulin mRNA and other deflagellation-induced RNAs in Chlamydomonas reinhardi

1986 ◽  
Vol 6 (1) ◽  
pp. 54-61
Author(s):  
E J Baker ◽  
L R Keller ◽  
J A Schloss ◽  
J L Rosenbaum
Keyword(s):  
Protein Synthesis ◽  
Transcriptional Control ◽  
Protein S ◽  
Protein Synthesis Inhibitors ◽  
Control Factors ◽  
Flagellar Proteins ◽  
The Stability ◽  
And Control

After flagellar detachment in Chlamydomonas reinhardi, there is a rapid synthesis and accumulation of mRNAs for tubulin and other flagellar proteins. Maximum levels of these mRNAs (flagellar RNAs) are reached within 1 h after deflagellation, after which they are rapidly degraded to their predeflagellation levels. The degradation of alpha- and beta-tubulin RNAs was shown to be due to the shortening of their half-lives after accumulation (Baker et al., J. Cell Biol. 99:2074-2081, 1984). Deflagellation in the presence of protein synthesis inhibitors results in the accumulation of tubulin and other flagellar mRNAs by kinetics similar to those of controls. However, unlike controls, in which the accumulated mRNAs are rapidly degraded, these mRNAs are stabilized in cycloheximide. The stabilization by cycloheximide is specific for the flagellar mRNAs accumulated after deflagellation, since there is no change in the levels of flagellar mRNAs in nondeflagellated (uninduced) cells in the presence of cycloheximide. The kinetics of flagellar mRNA synthesis after deflagellation are shown to be the same in cycloheximide-treated and control cells by in vivo labeling and in vitro nuclear runoff experiments. These results show that protein synthesis is not required for the induced synthesis of flagellar mRNAs, and that all necessary transcriptional control factors are present in the cell before deflagellation, but that protein synthesis is required for the accelerated degradation of the accumulated flagellar mRNAs. Since cycloheximide prevents the induced synthesis and accumulation of flagellar proteins, it is possible that the product(s) of protein synthesis required for the accelerated decay of these mRNAs is a flagellar protein(s). The possibility that one or more flagellar proteins autoregulate the stability of the flagellar mRNAs is discussed.

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