Identification of the taurine binding proteins from human placental brush border membrane

Placenta ◽  
1991 ◽  
Vol 12 (4) ◽  
pp. 382
Keyword(s):  
Brush Border ◽  
Binding Proteins ◽  
Brush Border Membrane

scholarly journals Binding Analyses of Bacillus thuringiensis Cry δ-Endotoxins Using Brush Border Membrane Vesicles of Ostrinia nubilalis

2001 ◽  
Vol 67 (2) ◽  
pp. 872-879 ◽  
Author(s):  
Gang Hua ◽  
Luke Masson ◽  
Juan Luis Jurat-Fuentes ◽  
George Schwab ◽  
Michael J. Adang
Keyword(s):  
Bacillus Thuringiensis ◽  
Binding Site ◽  
Brush Border ◽  
Ostrinia Nubilalis ◽  
European Corn Borer ◽  
Binding Proteins ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Brush Border Membrane Vesicles ◽  
Cry Toxin

ABSTRACT Transgenic corn expressing the Bacillus thuringiensisCry1Ab gene is highly insecticidal to Ostrinia nubilalis(European corn borer) larvae. We ascertained whether Cry1F, Cry9C, or Cry9E recognizes the Cry1Ab binding site on the O. nubilalis brush border by three approaches. An optical biosensor technology based on surface plasmon resonance measured binding of brush border membrane vesicles (BBMV) injected over a surface of immobilized Cry toxin. Preincubation with Cry1Ab reduced BBMV binding to immobilized Cry1Ab, whereas preincubation with Cry1F, Cry9C, or Cry9E did not inhibit BBMV binding. BBMV binding to a Cry1F-coated surface was reduced when vesicles were preincubated in Cry1F or Cry1Ab but not Cry9C or Cry9E. A radioligand approach measured 125I-Cry1Ab toxin binding to BBMV in the presence of homologous (Cry1Ab) and heterologous (Cry1Ac, Cry1F, Cry9C, or Cry9E) toxins. Unlabeled Cry1Ac effectively competed for 125I-Cry1Ab binding in a manner comparable to Cry1Ab itself. Unlabeled Cry9C and Cry9E toxins did not inhibit 125I-Cry1Ab binding to BBMV. Cry1F inhibited125I-Cry1Ab binding at concentrations greater than 500 nM. Cry1F had low-level affinity for the Cry1Ab binding site. Ligand blot analysis identified Cry1Ab, Cry1Ac, and Cry1F binding proteins in BBMV. The major Cry1Ab signals on ligand blots were at 145 kDa and 154 kDa, but a strong signal was present at 220 kDa and a weak signal was present at 167 kDa. Cry1Ac and Cry1F binding proteins were detected at 220 and 154 kDa. Anti-Manduca sexta aminopeptidase serum recognized proteins of 145, 154, and 167 kDa, and anti-cadherin serum recognized the 220 kDa protein. We speculate that isoforms of aminopeptidase and cadherin in the brush border membrane serve as Cry1Ab, Cry1Ac, and Cry1F binding proteins.

scholarly journals Radiation-inactivation analysis of the Na+/bile acid co-transport system from rabbit ileum

1995 ◽  
Vol 306 (1) ◽  
pp. 241-246 ◽  
Author(s):  
W Kramer ◽  
F Girbig ◽  
U Gutjahr ◽  
S Kowalewski
Keyword(s):  
Bile Acid ◽  
Transport System ◽  
Brush Border ◽  
Binding Proteins ◽  
Brush Border Membrane ◽  
High Energy ◽  
Target Size ◽  
Rabbit Ileum ◽  
Radiation Inactivation ◽  
Bile Acid Binding

The functional-unit molecular size of the Na+/bile acid cotransport system and the apparent target size of the bile-acid-binding proteins in brush-border membrane vesicles from rabbit ileum were determined by radiation inactivation with high-energy electrons. The size of the functional transporting unit for Na(+)-dependent taurocholate uptake was determined to 451 +/- 35 kDa, whereas an apparent molecular mass of 434 +/- 39 kDa was measured for the Na(+)-dependent D-glucose transport system. Proteins of 93 kDa and 14 kDa were identified as putative protein components of the ileal Na+/bile acid cotransporter in the rabbit ileum, whereas a protein of 87 kDa may be involved in passive intestinal bile acid uptake. Photoaffinity labelling with 3- and 7-azi-derivatives of taurocholate revealed a target size of 229 +/- 10 kDa for the 93 kDa protein, and 132 +/- 23 kDa for the 14 kDa protein. These findings indicate that the ileal Na+/bile acid co-transport system is in its functional state a protein complex composed of several subunits. The functional molecular sizes for Na(+)-dependent transport activity and the bile-acid-binding proteins suggest that the Na+/bile acid co-transporter from rabbit ileum is a homotetramer (AB)4 composed of four AB subunits, where A represents the integral 93 kDa and B the peripheral 14 kDa brush-border membrane protein.

Lipid absorptions passing through the unstirred layers, brush-border membrane, and beyond

1993 ◽  
Vol 71 (8) ◽  
pp. 531-555 ◽  
Author(s):  
A. B. R. Thomson ◽  
C. Schoeller ◽  
M. Keelan ◽  
L. Smith ◽  
M. T. Clandinin
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Brush Border ◽  
Binding Proteins ◽  
Brush Border Membrane ◽  
Water Layer ◽  
Lipid Binding ◽  
Dietary Lipids ◽  
Unstirred Water Layer ◽  
Lipid Binding Proteins

Lipids are components of our diet and luminal secretions, with physicochemical characteristics that determine their digestion and absorption in the gastrointestinal tract. Lipids include triglycerides, phospholipids, and cholesterol. Dietary lipids contain approximately 97% triglycerides, with small amounts of phospholipids and cholesterol. These components are important in cell membrane composition, fluidity, peroxidation, prostaglandin and leukotriene synthesis, and cellular metabolic processes. Lipids are implicated in the mechanisms of brain development, inflammatory processes, atherosclerosis, carcinogenesis, aging, and cell renewal. Duodenal hydrolysis of dietary lipids and biliary phospholipids and cholesterol is carried out by pancreatic lipase, colipase, phospholipase A2, and cholesterol esterase. Bile acid solubilization results in mixed micelles and liposomes, in gel and liquid crystal phases. Lipid digestion products pass across the intestinal unstirred water layer. For long-chain fatty acids and cholesterol, passage across the unstirred water layer is rate limiting, whereas passage of short- and medium-chain fatty acids is limited by the brush-border membrane. Within the unstirred water layer, an acidic microclimate aids micellar dissociation so that protonated, and to a lesser extent, nonprotonated monomers then pass across the intestinal brush-border membrane. Absorptive mechanisms have been studied extensively in relation to lipid composition, fatty acid chain length, degree of unsaturation, essential fatty acid content, phospholipid components, and cholesterol. Enterocytes may take up lipids from the intestinal lumen or from lipoproteins of the bloodstream, but these pools are likely to be functionally distinct. Recent advances are reviewed, including recent advances in the area of microclimates, compartmentation, lipid binding proteins, intracellular trafficking, intestinal lipoproteins, release of lipids across the basolateral membrane, and dietary effects.Key words: diet effects, lipid binding proteins, lipoproteins.

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