Structure of clathrin-coated vesicles from contrast-variation small-angle neutron scattering data
Previously published small-angle neutron scattering data from clathrin-coated vesicles have been analyzed in terms of a structural model. The data consist of contrast variation measurements at three different D2O solvent concentrations. 0%, 42%, and 75%. The model used for interpreting the data has spherical symmetry and explicitly takes into account polydispersity, which is described by a Gaussian distribution. A constant thickness of the clathrin coats is assumed. The fitting of the model shows that the coated vesicles consist of a low-density outer protein shell (clathrin) and a central protein shell (accessory polypeptides and receptors) of approximately six times higher denisty. The polydispersity of the samples is about 90 Å (full-width-at-half-maximum value) and the average outer radius is approximately 400 Å. The inner high-density shell has an inner and outer radius of 115 and 190 Å, respectively. A simultaneous fit to the three neutron contrast variation dat sets identifies the lipid membrane with a thickness of 40 Å and an outer radius of 196 Å. The molecular mass of the average particle is 27 × 106 Da. The coated vesicles consist, on average, of approximately 85% protein and 15% lipids. About 40% of the protein mass is situated in the central high-density shell which gives a large amount of protein in the lipid membrane. The densities of the central shell and the lipid membrane show that they hydration is small in the central region.
Key wordsSmall-angle neutron scattering contrast variation clathrin vesicles molecular structure
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