ジャーナル: Proc Natl Acad Sci U S A / 年: 2009 タイトル: The eye lens chaperone alpha-crystallin forms defined globular assemblies. 著者: Jirka Peschek / Nathalie Braun / Titus M Franzmann / Yannis Georgalis / Martin Haslbeck / Sevil Weinkauf / Johannes Buchner / 要旨: Alpha-crystallins are molecular chaperones that protect vertebrate eye lens proteins from detrimental protein aggregation. alphaB-Crystallin, 1 of the 2 alpha-crystallin isoforms, is also associated ...Alpha-crystallins are molecular chaperones that protect vertebrate eye lens proteins from detrimental protein aggregation. alphaB-Crystallin, 1 of the 2 alpha-crystallin isoforms, is also associated with myopathies and neuropathological diseases. Despite the importance of alpha-crystallins in protein homeostasis, only little is known about their quaternary structures because of their seemingly polydisperse nature. Here, we analyzed the structures of recombinant alpha-crystallins using biophysical methods. In contrast to previous reports, we show that alphaB-crystallin assembles into defined oligomers consisting of 24 subunits. The 3-dimensional (3D) reconstruction of alphaB-crystallin by electron microscopy reveals a sphere-like structure with large openings to the interior of the protein. alphaA-Crystallin forms, in addition to complexes of 24 subunits, also smaller oligomers and large clusters consisting of individual oligomers. This propensity might explain the previously reported polydisperse nature of alpha-crystallin.
After correction of contrast transfer function by phase flipping the reconstructions have been performed by iterative cycles of MRA, MSA, classification and angular reconstitution of the obtained class averages. See also publication Peschek et al., 2009. The eye lens chaperone alpha-crystallin forms defined globular assemblies. PNAS 106
CTF補正
詳細: Phase flipping of each particle
最終 再構成
想定した対称性 - 点群: T (正4面体型対称) / アルゴリズム: OTHER / 解像度のタイプ: BY AUTHOR / 解像度: 20.0 Å / 解像度の算出法: FSC 0.5 CUT-OFF / ソフトウェア - 名称: Imagic / 詳細: Final maps were calculated from 40 class averages / 使用した粒子像数: 2565