3D reconstructions of a cryoET 17 nm nascent HDL particle by IPET.

<p>(A) An individual targeted nascent HDL particle embedded in vitreous ice was imaged by the cryoET technique. The tilt images of a targeted particle were windowed from the tilt series of cryoET micrographs after the CTF was corrected by TOMOCTF. Nine represented tilted views of a targeted 17 nm HDL particle were shown in leftmost column. These selected tilt images were from 81 tilt micrographs that were taken at the specified tilt angles. The other six columns in each grid showed the results of progressive refinement from certain iterations. (B) Reconstructed to 3D density map. The high-density portion corresponding to proteins, apolipoprotein A-I (apoA-I), was formed in a ring shape. (C) By docking the double-helices into the ring-shaped density, the size suggests three apoA-I molecules exist in a 17 nm HDL particle. (D) Another targeted 17 nm HDL particle was imaged and reconstructed for 3D density map. (E–F) The 3D reconstruction showed the similar structural feature to the first HDL particle, suggesting our cryoET reconstructions are consistent as reported by cryoEM observation <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0030249#pone.0030249-vanAntwerpen1" target="_blank">[51]</a>.