Transcortin interaction with human syncytiotrophoblast

Interactions of transcortin (corticosteroid-binding globulin, CBG) variants, nCBG and rCBG, present in the blood of pregnant women, and microvesicular fraction of the brush border membrane of human placental syncytiotrophoblast at 23 + 2 C were studied. Interaction of nCBG in complex with a steroid with each of the two types for specific binding was found associated with transmcmbranous transfer of glycoprotein. Interaction of rCBG with binding sites of both types did not involve subsequent glycoprotein transfer through the membrane. Possibility of penetration of only one CBG variant through syncytiotrophoblast membrane suggests the presence of different mechanisms of these glycoproteins' participation in the hormonal effects of steroids associated with them.

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Specific binding of Bacillus thuringiensis Cry1Ea toxin, and Cry1Ac and Cry1Fa competition analyses in Anticarsia gemmatalis and Chrysodeixis includens

Scientific Reports ◽

10.1038/s41598-019-54850-3 ◽

2019 ◽

Vol 9 (1) ◽

Author(s):

Yolanda Bel ◽

Marc Zack ◽

Ken Narva ◽

Baltasar Escriche

Keyword(s):

Bacillus Thuringiensis ◽

Brush Border ◽

Binding Sites ◽

Brush Border Membrane ◽

Specific Binding ◽

Anticarsia Gemmatalis ◽

Binding Studies ◽

Velvetbean Caterpillar ◽

Competition Binding ◽

Chrysodeixis Includens

AbstractAnticarsia gemmatalis (velvetbean caterpillar) and Chrysodeixis includens (soybean looper) are two important defoliation pests of soybeans. In the present study, we have investigated the susceptibility and brush border membrane-binding properties of both species to Bacillus thuringiensis Cry1Ea toxin. Bioassays performed in first-instar larvae demonstrated potent activity against both soybean pests in terms of mortality or practical mortality. Competition-binding studies carried out with 125Iodine-labelled Cry1Ea, demonstrated the presence of specific binding sites on the midgut brush border membrane vesicles (BBMV) of both insect species. Heterologous competition-binding experiments indicated that Cry1Ea does not share binding sites with Cry1Ac or Cry1Fa in either soybean pest. This study contributes to the knowledge of Cry1Ea toxicity and midgut binding sites in A. gemmatalis and C. includens and sheds light on the cross-resistance potential of Cry1Ea with other Bt proteins aimed at controlling lepidopteran pests in soybeans.

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Critical domains in the specific binding of radiolabelled Vip3Af insecticidal protein to brush border membrane vesicles from Spodoptera spp. and cultured insect cells

Applied and Environmental Microbiology ◽

10.1128/aem.01787-21 ◽

2021 ◽

Author(s):

Yudong Quan ◽

Maria Lázaro-Berenguer ◽

Patricia Hernández-Martínez ◽

Juan Ferré

Keyword(s):

Brush Border ◽

Binding Sites ◽

Brush Border Membrane ◽

Ex Vivo ◽

Specific Binding ◽

Membrane Vesicles ◽

Brush Border Membrane Vesicles ◽

Cry Proteins ◽

Competition Binding

Vegetative insecticidal proteins (Vip3) from Bacillus thuringiensis have been used, in combination with Cry proteins, to better control insect pests and as a strategy to delay the evolution of resistance to Cry proteins in Bt crops (crops protected from insect attack by the expression of proteins from B. thuringiensis ). In this study, we have set up the conditions to analyze the specific binding of 125 I-Vip3Af to Spodoptera frugiperda and Spodoptera exigua brush border membrane vesicles (BBMV). Heterologous competition binding experiments revealed that Vip3Aa shares the same binding sites with Vip3Af, but that Vip3Ca does not recognize all of them. As expected, Cry1Ac and Cry1F did not compete for Vip3Af binding sites. By trypsin treatment of selected alanine-mutants, we were able to generate truncated versions of Vip3Af. Their use as competitors with 125 I-Vip3Af indicated that only those molecules containing domains I to III (DI-III and DI-IV) were able to compete with the trypsin-activated Vip3Af protein for binding, and that molecules only containing either domain IV or domains IV and V (DIV and DIV-V) were unable to compete with Vip3Af. These results were further confirmed with competition binding experiments using 125 I-DI-III. In addition, the truncated protein 125 I-DI-III also bound specifically to Sf21 cells. Cell viability assays showed that the truncated proteins DI-III and DI-IV were as toxic to Sf21 cells as the activated Vip3Af, suggesting that domains IV and V are not necessary for the toxicity to Sf21 cells, in contrast to their requirement in vivo. IMPORTANCE This study shows that Vip3Af binding sites are fully shared with Vip3Aa, only partially shared with Vip3Ca, and not shared with Cry1Ac and Cry1F in two Spodoptera spp. Truncated versions of Vip3Af revealed that only domains I to III were necessary for the specific binding, most likely because they can form the functional tetrameric oligomer and because domain III is supposed to contain the binding epitopes. In contrast to results obtained in vivo (bioassays against larvae), domains IV and V are not necessary for the ex vivo toxicity to Sf21 cells.

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Binding Sites for Bacillus thuringiensis Cry2Ae Toxin on Heliothine Brush Border Membrane Vesicles Are Not Shared with Cry1A, Cry1F, or Vip3A Toxin

Applied and Environmental Microbiology ◽

10.1128/aem.02791-10 ◽

2011 ◽

Vol 77 (10) ◽

pp. 3182-3188 ◽

Cited By ~ 67

Author(s):

C. Gouffon ◽

A. Van Vliet ◽

J. Van Rie ◽

S. Jansens ◽

J. L. Jurat-Fuentes

Keyword(s):

Bacillus Thuringiensis ◽

Brush Border ◽

Binding Sites ◽

Brush Border Membrane ◽

Specific Binding ◽

Membrane Vesicles ◽

Brush Border Membrane Vesicles ◽

Target Range ◽

Content Type ◽

Bt Toxins

ABSTRACTThe use of combinations ofBacillus thuringiensis(Bt) toxins with diverse modes of action for insect pest control has been proposed as the most efficient strategy to increase target range and delay the onset of insect resistance. Considering that most cases of cross-resistance to Bt toxins in laboratory-selected insect colonies are due to alteration of common toxin binding sites, independent modes of action can be defined as toxins sharing limited or no binding sites in brush border membrane vesicles (BBMV) prepared from the target insect larvae. In this paper, we report on the specific binding of Cry2Ae toxin to binding sites on BBMV from larvae of the three most commercially relevant heliothine species,Heliothis virescens,Helicoverpa zea, andHelicoverpa armigera. Using chromatographic purification under reducing conditions before labeling, we detected specific binding of radiolabeled Cry2Ae, which allowed us to perform competition assays using Cry1Ab, Cry1Ac, Cry1Fa, Vip3A, Cry2Ae, and Cry2Ab toxins as competitors. In these assays, Cry2Ae binding sites were shared with Cry2Ab but not with the tested Cry1 or Vip3A toxins. Our data support the use of Cry2Ae toxin in combination with Cry1 or Vip3A toxins in strategies to increase target range and delay the onset of heliothine resistance.

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Internalization and intracellular transport of folate-binding protein in rat kidney proximal tubule

AJP Cell Physiology ◽

10.1152/ajpcell.1993.264.2.c302 ◽

1993 ◽

Vol 264 (2) ◽

pp. C302-C310 ◽

Cited By ~ 89

Author(s):

H. Birn ◽

J. Selhub ◽

E. I. Christensen

Keyword(s):

Plasma Membrane ◽

Proximal Tubule ◽

Brush Border ◽

Intracellular Transport ◽

Brush Border Membrane ◽

Specific Binding ◽

Binding Protein ◽

Rat Kidney ◽

Folate Binding Protein

Folate-binding protein (FBP) is involved in folate reabsorption in the renal proximal tubule. Immunocytochemical studies have located FBP to the brush-border membrane, endocytic vacuoles, and dense apical tubules. We applied the same polyclonal antibody (anti-FBP) against FBP to investigate the dynamic relationship between FBP in the different compartments by microinjecting the antibody into rat kidney proximal tubules in situ. Specific binding of anti-FBP in vivo to the brush-border membrane was followed by fixation at various times. Protein A-gold labeling shows that anti-FBP is transported from endocytic invaginations into vacuoles followed by transport into dense apical tubules within 15 s. Thus FBP is rapidly internalized, and together with previous studies this study strongly suggests recycling of FBP back to the luminal plasma membrane through dense apical tubules. The results are consistent with reabsorption of folate through endocytosis of the FBP-folate complex followed by dissociation and recycling of FBP. When time is allowed there is a steady accumulation of FBP in dense apical tubules combined with an increase in surface density of the same compartment. A possible explanation involves partial inhibition of the fusion between dense apical tubules and plasma membrane because of the anti-FBP labeling of the receptor.

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Iron uptake from transferrin and lactoferrin by rat intestinal brush-border membrane vesicles

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1990.258.4.g535 ◽

1990 ◽

Vol 258 (4) ◽

pp. G535-G541 ◽

Cited By ~ 7

Author(s):

H. Kawakami ◽

S. Dosako ◽

B. Lonnerdal

Keyword(s):

Brush Border ◽

Brush Border Membrane ◽

Specific Binding ◽

Membrane Vesicles ◽

Brush Border Membrane Vesicles ◽

Human Lactoferrin ◽

Affinity Constant ◽

Bovine Lactoferrin ◽

Intestinal Brush Border Membrane ◽

Intestinal Brush Border

Interaction of 59Fe-labeled rat transferrin, human lactoferrin, and bovine lactoferrin with rat small intestinal brush-border membrane vesicles was investigated with the use of a rapid filtration technique. Specific binding of 59Fe-labeled rat transferrin and bovine lactoferrin to brush-border membrane vesicles from suckling and adult rats was identified. In contrast, no binding of human lactoferrin occurred. The presence of transferrin receptors on the brush-border membrane of suckling rats was confirmed by immunoblotting, and the molecular mass of the receptor was 96 kDa under nonreducing conditions. Scatchard plot analysis indicated 2.4 x 10(14) binding sites/mg of membrane protein with an affinity constant (Ka) of 4.9 x 10(6) M-1 for rat milk transferrin and 2.2 x 10(14) bi

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Fluorescent analyses of Bacillus thuringiensis Cry1Fa and Cry1Ab toxin binding sites on brush border membrane vesicles of Ostrinia nubilalis (Hübner), Diatraea grandiosella (Dyar), and Helicoverpa zea (Boddie) larvae

Pesticide Biochemistry and Physiology ◽

10.1016/j.pestbp.2020.104592 ◽

2020 ◽

Vol 167 ◽

pp. 104592

Author(s):

Reben Raeman ◽

Gang Hua ◽

Qi Zhang ◽

Michael J. Adang

Keyword(s):

Bacillus Thuringiensis ◽

Brush Border ◽

Ostrinia Nubilalis ◽

Binding Sites ◽

Helicoverpa Zea ◽

Brush Border Membrane ◽

Membrane Vesicles ◽

Diatraea Grandiosella ◽

Toxin Binding ◽

Cry1ab Toxin

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Extravascular CBG-like sites in rat kidney and mineralocorticoid receptor specificity

AJP Renal Physiology ◽

10.1152/ajprenal.1984.246.2.f227 ◽

1984 ◽

Vol 246 (2) ◽

pp. F227-F233 ◽

Cited By ~ 1

Author(s):

G. Stephenson ◽

Z. Krozowski ◽

J. W. Funder

Keyword(s):

Binding Sites ◽

Specific Binding ◽

Rat Kidney ◽

Renal Medulla ◽

Limited Capacity ◽

Outer Medulla ◽

Corticosteroid Binding Globulin ◽

Countercurrent Exchange ◽

Local Accumulation ◽

Intrarenal Distribution

To determine the intrarenal distribution of extravascular corticosteroid-binding globulin- (CBG) like sites, we measured the specific binding of [3H]corticosterone to supernatants prepared from papilla-inner medulla, outer medulla, and cortex from adrenalectomized rats. Renal papilla-inner medulla of exhaustively perfused kidneys contained 8-20 times higher concentrations of such sites than cortex or outer medulla. The ontogeny and steroid specificities of such sites were identical to those of plasma CBG; their molar concentration in the inner medulla-papilla was 4 times that of plasma CBG, consistent with local accumulation of CBG. Cytosols from all three zones bound [3H]aldosterone in the presence of RU-26988, a highly specific synthetic glucocorticoid, with high affinity (Kd 4 degrees C, 0.3-0.4 X 10(-9) M) and limited capacity (papilla-inner medulla, 23-34; outer medulla, 15-16; cortex, 12-17 fmol/mg). In papilla-inner medulla the apparent specificity of such [3H]aldosterone binding sites was aldosterone greater than corticosterone greater than dexamethasone, in contrast to aldosterone = corticosterone greater than dexamethasone in outer medulla and cortex. We propose that extravascular CBG confers mineralocorticoid specificity on the papilla-inner medulla [3H]aldosterone binding sites. In addition, given the higher levels of extravascular than intravascular CBG and the recurrent vascular architecture of the renal medulla-papilla, a countercurrent exchange model is proposed for renewable sequestration of corticosterone in the region.

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