Purification and properties of a membrane-bound insulin binding protein, a putative receptor, from Neurospora crassa

Biochemistry ◽  
1991 ◽  
Vol 30 (3) ◽  
pp. 682-688 ◽  
Author(s):  
Hemanta K. Kole ◽  
Ganapathy Muthukumar ◽  
John Lenard
Keyword(s):  
Neurospora Crassa ◽  
Binding Protein ◽  
Protein A ◽  
Insulin Binding ◽  
Putative Receptor ◽  
Purification And Properties ◽  
Membrane Bound

scholarly journals The structure of lactoferrin-binding protein B fromNeisseria meningitidissuggests roles in iron acquisition and neutralization of host defences

2014 ◽  
Vol 70 (10) ◽  
pp. 1312-1317 ◽  
Author(s):  
Cory L. Brooks ◽  
Elena Arutyunova ◽  
M. Joanne Lemieux
Keyword(s):  
Binding Protein ◽  
Iron Acquisition ◽  
Protein A ◽  
Transport Systems ◽  
Cationic Peptide ◽  
Moraxella Bovis ◽  
Component Systems ◽  
Two Component Systems ◽  
Membrane Bound ◽  
Protein B

Pathogens have evolved a range of mechanisms to acquire iron from the host during infection. Several Gram-negative pathogens including members of the generaNeisseriaandMoraxellahave evolved two-component systems that can extract iron from the host glycoproteins lactoferrin and transferrin. The homologous iron-transport systems consist of a membrane-bound transporter and an accessory lipoprotein. While the mechanism behind iron acquisition from transferrin is well understood, relatively little is known regarding how iron is extracted from lactoferrin. Here, the crystal structure of the N-terminal domain (N-lobe) of the accessory lipoprotein lactoferrin-binding protein B (LbpB) from the pathogenNeisseria meningitidisis reported. The structure is highly homologous to the previously determined structures of the accessory lipoprotein transferrin-binding protein B (TbpB) and LbpB from the bovine pathogenMoraxella bovis. Docking the LbpB structure with lactoferrin reveals extensive binding interactions with the N1 subdomain of lactoferrin. The nature of the interaction precludes apolactoferrin from binding LbpB, ensuring the specificity of iron-loaded lactoferrin. The specificity of LbpB safeguards proper delivery of iron-bound lactoferrin to the transporter lactoferrin-binding protein A (LbpA). The structure also reveals a possible secondary role for LbpB in protecting the bacteria from host defences. Following proteolytic digestion of lactoferrin, a cationic peptide derived from the N-terminus is released. This peptide, called lactoferricin, exhibits potent antimicrobial effects. The docked model of LbpB with lactoferrin reveals that LbpB interacts extensively with the N-terminal lactoferricin region. This may provide a venue for preventing the production of the peptide by proteolysis, or directly sequestering the peptide, protecting the bacteria from the toxic effects of lactoferricin.

scholarly journals Interactions of small molecules with phospholipid bilayers. Binding to egg phosphatidylcholine of some uncharged molecules (2-acetylaminofluorene, 4-dimethylaminoazobenzene, oestrone and testosterone) that bind to ligandin and aminoazo-dye-binding protein A

1979 ◽  
Vol 180 (2) ◽  
pp. 319-326 ◽  
Author(s):  
Edward Tipping ◽  
Brian Ketterer ◽  
Lucia Christodoulides
Keyword(s):  
Lipid Bilayers ◽  
Partition Coefficients ◽  
Intracellular Transport ◽  
Binding Protein ◽  
Equilibrium Dialysis ◽  
Protein A ◽  
Molar Ratio ◽  
Intracellular Proteins ◽  
Dye Binding ◽  
Membrane Bound

1. To assess the possible involvement of ligandin and aminoazo-dye-binding protein A in intracellular transport it is necessary to know how their ligands, most of which are molecules with hydrophobic moieties, interact with cellular membranes. To obtain such information we have examined the interactions of 2-acetylaminofluorene, 4-dimethylaminoazobenzene, oestrone and testosterone with aqueous dispersions of egg phosphatidylcholine and egg phosphatidylcholine/cholesterol (1:1, molar ratio) by equilibrium dialysis and spectrophotometry. 2. At 25°C and pH7.4, the partition coefficients for binding to phosphatidylcholine [expressed as (mol of ligand bound/mol of phosphatidylcholine)/unbound ligand concentration] were: for 2-acetylaminofluorene, 5.0×103 litre·mol−1; for 4-dimethylaminoazobenzene, 2.1×104 litre·mol−1; for oestrone, 3.1×103 litre·mol−1; and for testosterone, 4.2×102 litre·mol−1. In the ranges studied these values were independent of concentration. The results for the two steroids confirm those of Heap, Symons & Watkins [(1970) Biochim. Biophys. Acta218, 482–495]. 3. The introduction of cholesterol into the lipid bilayers caused large decreases in the partition coefficients of oestrone and testosterone, but had relatively little effect on the binding of 2-acetylaminofluorene and 4-dimethylaminoazobenzene. 4. By assuming that the interactions with egg phosphatidylcholine bilayers resemble those with the phospholipid components of mammalian intracellular membranes the phosphatidylcholine partition coefficients, together with data for binding to the intracellular proteins ligandin and aminoazo-dye-binding protein A, enable the subcellular distributions of the four compounds to be estimated. For the rat hepatocyte up to 98, 99, 89 and 58% of the total 2-acetylaminofluorene, 4-dimethylaminoazobenzene, oestrone and testosterone respectively may be membrane-bound.

Binding of Human Platelet Glycoprotein lb and Actin to Fragments of Actin-Binding Protein

1992 ◽  
Vol 67 (02) ◽  
pp. 252-257 ◽  
Author(s):  
Anne M Aakhus ◽  
J Michael Wilkinson ◽  
Nils Olav Solum
Keyword(s):  
Actin Filaments ◽  
High Speed ◽  
Binding Protein ◽  
Protein A ◽  
Actin Binding ◽  
Platelet Glycoprotein ◽  
Actin Binding Protein ◽  
Crossed Immunoelectrophoresis ◽  
Triton X ◽  
Calpain Inhibitors

SummaryActin-binding protein (ABP) is degraded into fragments of 190 and 90 kDa by calpain. A monoclonal antibody (MAb TI10) against the 90 kDa fragment of ABP coprecipitated with the glycoprotein lb (GP lb) peak observed on crossed immunoelectrophoresis of Triton X-100 extracts of platelets prepared without calpain inhibitors. MAb PM6/317 against the 190 kDa fragment was not coprecipitated with the GP lb peak under such conditions. The 90 kDa fragment was adsorbed on protein A agarose from extracts that had been preincubated with antibodies to GP lb. This supports the idea that the GP Ib-ABP interaction resides in the 90 kDa region of ABP. GP lb was sedimented with the Triton-insoluble actin filaments in trace amounts only, and only after high speed centrifugation (100,000 × g, 3 h). Both the 190 kDa and the 90 kDa fragments of ABP were sedimented with the Triton-insoluble actin filaments.

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