Rat liver proteins capable of transferring phosphatidylethanolamine. Purification and transfer activity for other phospholipids and cholesterol.

Bloj, Bernabé; Zilversmit, D. B.

doi:10.1016/s0021-9258(17)40593-x

Cited by 281 publications

(27 citation statements)

References 28 publications

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“…Assuming the density of liver is 1 g/cm3, the dry weight of the cell is 40% with 10% of that being lipid; the cellular concentration of an average lipid molecule of Mr 1000 is 40 mM. The concentration of soluble nsLTP in rat liver supernatant can be calculated to range between 0.5 and 8 µ (Bloj & Zilversmit, 1977;Noland et al, 1980;Poorthuis et al, 1981;Trzaskos & Gaylor, 1983). The best-fit parameters for the combined model (Table II) can be used to calculate the rates of P-C12-NBD-PC transfer from vesicles to nsLTP through each separate pathway.…”

Section: Resultsmentioning

confidence: 99%

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Kinetics of fluorescent-labeled phosphatidylcholine transfer between nonspecific lipid transfer protein and phospholipid vesicles

Nichols¹

1988

Biochemistry

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Recently, rat liver nonspecific lipid transfer protein (nsLTP) was shown to form a fluorescent complex when allowed to equilibrate with self-quenching vesicles prepared from the fluorescent phospholipid 1-palmitoyl-2-[12-[(7-nitro-2,1,3-benzoxadiazol-4- yl)amino]dodecanoyl]phosphatidylcholine (P-C12-NBD-PC) [Nichols, J. W. (1987) J. Biol. Chem. 262, 14172-14177]. Investigation of the mechanism of complex formation was continued by studying the kinetics of transfer of P-C12-NBD-PC between nsLTP and phospholipid vesicles using a transfer assay based on resonance energy transfer between P-C12-NBD-PC and N-(lissamine rhodamine B sulfonyl)dioleoylphosphatidylethanolamine. The principles of mass action kinetics (which predict initial lipid transfer rates as a function of protein and vesicle concentration) were used to derive equations for two distinct mechanisms: lipid transfer by the diffusion of monomers through the aqueous phase and lipid transfer during nsLTP-membrane collisions. The results of these kinetics studies indicated that the model for neither mechanism alone adequately predicted the initial rates of formation and dissolution of the P-C12-NBD-PC-nsLTP complex. The initial rate kinetics for both processes were predicted best by a model in which monomer diffusion and collision-dependent transfer occur simultaneously. These data support the hypothesis that the phospholipid-nsLTP complex functions as an intermediate in the transfer of phospholipids between membranes.

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Section: Resultsmentioning

confidence: 99%

“…^Nonspecific lipid transfer protein (nsLTP)1 stimulates the transfer of a wide range of lipids between membranes (Bloj & Zilversmit, 1977. Recently, nsLTP was shown to form a water-soluble phospholipid-nsLTP complex when allowed to equilibrate with bilayer vesicles prepared from fluorescent-labeled phospholipid, P-C12-NBD-PC (Nichols, 1987a).…”

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Kinetics of fluorescent-labeled phosphatidylcholine transfer between nonspecific lipid transfer protein and phospholipid vesicles

Nichols¹

1988

Biochemistry

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“…Sterol carrier protein 2 (SCP2, also called nonspecific lipid-transfer protein) is a 13 kDa protein that, in vitro, catalyzes intermembrane movement of PCs and a variety of other phospholipid classes as well as sterols (8)(9)(10). In steroidogenic tissues where it is expressed, SCP2 is localized principally in peroxisomes (11).…”

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confidence: 99%

Submicellar bile salts stimulate phosphatidylcholine transfer activity of sterol carrier protein 2

Leonard

Cohen

1998

Journal of Lipid Research

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To explore a potential role for sterol carrier protein 2 (SCP2, also known as non-specific lipid transfer protein) in hepatocellular phospholipid trafficking, we examined the influence of submicellar bile salt concentrations on phosphatidylcholine (PC) transfer activity of SCP2. We measured rate constants for first-order transfer of sn -1 palmitoyl, sn -2 parinaroyl PC, a naturally fluorescent selfquenching phospholipid between model membranes. Purified bovine liver SCP2 promoted transfer of PC from donor to acceptor small unilamellar vesicles. Taurine-and glycine-conjugated bile salts (anionic steroid detergent-like molecules), at concentrations well below their critical micellar concentrations, stimulated PC transfer activity of SCP2 80-to 140-fold. Rate constants increased in proportion to bile salt concentration, temperature, and bile saltmembrane binding affinity. Sodium taurofusidate, a conjugated fungal bile salt analog, also activated PC transfer whereas no effect was observed with the anionic and nonionic straight chain detergents sodium dodecyl sulfate and octylglucoside, respectively. Thermodynamic and kinetic analyses of PC transfer support a mechanism in which bile salts stimulate SCP2 activity by partitioning into donor vesicles and enhancing membrane association of SCP2. These results imply that under physiological conditions, SCP2 may contribute to hepatocellular selection and transport of biliary PCs.-Leonard, A. N., and D. E. Cohen. Submicellar bile salts stimulate phosphatidylcholine transfer activity of sterol carrier protein 2.

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“…Recent studies have shown that phospholipid translocation is reversible (14), whereas that of LPS is not (14,17,20). There is no evidence in bacteria for the existence of phospholipid exchange proteins analogous to those in eukaryotes (6,14). The discovery by Bayer of 200 to 400 areas of contact, or zones of adhesion, between the inner and outer membranes of Escherichia coli K-12 (2) offered a potential solution to the problem of translocation.…”

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Bacteriophage P22 is not a likely probe for zones of adhesion between the inner and outer membranes of Salmonella typhimurium

Crowlesmith¹,

Schindler²,

Osborn³

1978

J Bacteriol

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Thin-section electron micrographs of plasmolyzed Salmonella typhimurium infected with bacteriophage P22 demonstrated that phage adsorbed to cells over sites of inner- and outer-membrane contact. Efforts were made to isolate such adsorption sites by infection of cells with 35S- and 32P-labeled phage and by separation of the membranes on sucrose gradients. At 37 degrees C, about 75% of the 35S radioactivity could be recovered in a region of intermediate density between the inner and outer membranes. This region (phi band) did not contain 32P. The gradient profile was independent of the multiplicity of infection (between 0.2 and 50) and of the presence or absence of chloramphenicol, dinitrophenol, or cyanide. However, ethylenediaminetetraacetate, when present during the infection step, prevented the formation of phi band. The density of phi band was at least 1.30 g/cm3, as demonstrated by prolonged centrifugation on a D2O-sucrose gradient. phi Band was shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electron microscopy to contain empty phage heads and contaminating cellular debris. In purified preparations, phage heads were the only structures, visible by negative staining, and very little cellular phospholipid or protein was associated with the phage proteins (less than 2% and 30% by weight, respectively, as determined by using [3H]glycerol or [3H]leucine). The residual cellular protein included all of the major outer-membrane proteins rather than any one specific protein. These results are interpreted as indicating that phi band probably does not contain adhesion site material stably associated with phage heads.

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Rat liver proteins capable of transferring phosphatidylethanolamine. Purification and transfer activity for other phospholipids and cholesterol.

Cited by 281 publications

References 28 publications

Kinetics of fluorescent-labeled phosphatidylcholine transfer between nonspecific lipid transfer protein and phospholipid vesicles

Kinetics of fluorescent-labeled phosphatidylcholine transfer between nonspecific lipid transfer protein and phospholipid vesicles

Submicellar bile salts stimulate phosphatidylcholine transfer activity of sterol carrier protein 2

Bacteriophage P22 is not a likely probe for zones of adhesion between the inner and outer membranes of Salmonella typhimurium

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