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- Ul Mushtaq, Ameeq, et al.
(författare)
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Neutron reflectometry and NMR spectroscopy of full-length Bcl-2 protein reveal its membrane localization and conformation
- 2021
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 4:1
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Tidskriftsartikel (refereegranskat)abstract
- B-cell lymphoma 2 (Bcl-2) proteins are the main regulators of mitochondrial apoptosis. Anti-apoptotic Bcl-2 proteins possess a hydrophobic tail-anchor enabling them to translocate to their target membrane and to shift into an active conformation where they inhibit pro-apoptotic Bcl-2 proteins to ensure cell survival. To address the unknown molecular basis of their cell-protecting functionality, we used intact human Bcl-2 protein natively residing at the mitochondrial outer membrane and applied neutron reflectometry and NMR spectroscopy. Here we show that the active full-length protein is entirely buried into its target membrane except for the regulatory flexible loop domain (FLD), which stretches into the aqueous exterior. The membrane location of Bcl-2 and its conformational state seems to be important for its cell-protecting activity, often infamously upregulated in cancers. Most likely, this situation enables the Bcl-2 protein to sequester pro-apoptotic Bcl-2 proteins at the membrane level while sensing cytosolic regulative signals via its FLD region. Through neutron reflectometry and NMR spectroscopy studies, Mushtaq et al study the full-length Bcl-2 protein reconstituted in lipid bilayers. They find that, in contrast to previously studied truncated, soluble protein versions, intact Bcl-2 is mainly embedded in the membrane with its regulatory loop highly flexible.
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| 2. |
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| 3. |
- Felippov, A., et al.
(författare)
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Diffusion and aggregation of Alzheimer's Aβ1-40 peptide in aqueous trifluoroethanol solutions as studied by pulsed field gradient NMR
- 2005
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Ingår i: Applied Magnetic Resonance. - 0937-9347 .- 1613-7507. ; 29:3, s. 439-449
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Tidskriftsartikel (refereegranskat)abstract
- Pulsed field gradient nuclear magnetic resonance technique was applied to measure the self-diffusion coefficient of Aβ1-40 peptide in trifluoroethanol (TFE) and mixed solvent TFE-water (D2O) buffer (pD 7.8) at 293 K. The data were analyzed on the basis of the Stokes model and the hard-sphere approach was used to estimate self-diffusion coefficients. It was found that the extent of the Aβ1-40 aggregation in TFE solutions depends on the concentration of the peptide and the sample preparation protocol. After soft mixing, i.e., without any additional mechanical pretreatment of the peptide, the peptide is present in the monomeric form in TFE solutions. However, the additional water-bath sonication of the sample during the dissolution of Aβ1-40 in TFE enforces oligomerization of the peptide with the size of aggregates ranging from tetra- to hexamers. An increase of D2O in the mixed TFE-D2O solvent of up to 75% leads to the aggregation of the larger part of the peptide. However, the components of self-diffusion coefficients related to low-mass Aβ1-40 oligomers (dimers and trimers) were not observed in the diffusion decay curves. The most probable explanation is that dimers and trimers are not the principal intermediate species in the aggregation of Aβ1-40 peptide (23 refs.)
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