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New data on the microtubule surface lattice
Author(s) -
Chrétien Denis,
Wade Richard H.
Publication year - 1991
Publication title -
biology of the cell
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.543
H-Index - 85
eISSN - 1768-322X
pISSN - 0248-4900
DOI - 10.1016/0248-4900(91)90062-r
Subject(s) - microtubule , axoneme , tubulin , biophysics , crystallography , lattice (music) , polymerization , biology , cilium , chemical physics , physics , microbiology and biotechnology , chemistry , flagellum , biochemistry , nuclear magnetic resonance , acoustics , gene , polymer
Summary— The in vitro polymerisation of tubulin is a remarkable example of protein self‐assembly in thet several closely related microtubule structures coexist on the polymerisation plateau. Unfixed and unstained in vitro assembled microtubules were observed in vitreous ice by cryo‐electron microscopy. New results are reported that considerably extend previous observations [47]. In ice, microtubule images have a distinctive contrast related to the number and skew of the photofilaments. The microtubules observed have from twelve to seventeen protofilaments. Comparison with thin sections of pelleted material allows a direct identification of images from microtubules with thirteen, fourteen and fifteen protofilaments. A surface lattice accommodation mechanism, previously proposed to explain how variable numbers of protofilaments can be incorporated into the basic thirteen protofilament structure, is described in detail. Our new experimental results are shown to be in overall agreement with the theoretical predictions. Only thirteen protofilament microtubules have unskewed protofilaments, this was confirmed by observations on axoneme fragments. The results imply that the microtubule surface lattice is based on a mixed packing which combines features of the standard A and B lattices.