Tubulin rings: Curved filaments with limited flexibility and two modes of association
- 1 January 1979
- journal article
- research article
- Published by Wiley in Journal of Supramolecular Structure
- Vol. 10 (4), 419-431
- https://doi.org/10.1002/jss.400100405
Abstract
Tubulin rings have been previously identified as composed of linear polymers of tubulin subunits, equivalent to a protofilament in the microtubule wall but in a curved rather than a straight conformation. We have examined and measured a number of different ring structures obtained under different conditions. The preferred curvature is indicated by a single ring of 380 Å outside diameter. Radially double rings consist of two coplanar rings of 460 Å and 350 Å outside diameter, held together by a pattern of eight identical contacts between the 40 Å subunits in the inner and outer rings. In some circumstances a larger ring, 570 Å diameter, can be added to the outside, or a smaller ring, 240 Å diameter, may be added to the inside of the radially double ring, in both cases repeating the pattern of eight radial contacts. The distortion of the filament from its relaxed 380 Å diameter curvature apparently can be made without disrupting the longitudinal bond between subunits in the filament, but must be stabilized by the energy of the radial contacts. All of these rings (single and radially double and triple) are observed to associate axially to form pairs or in some cases larger stacks. The radially double rings or an axially associated pair of these (quadruple ring) may also associate to form crystals. These are thin plates, up to 100 μm in extent and several μm thick which have been of limited use so far in diffraction studies because of irregularities in the packing of adjacent rings.Keywords
This publication has 29 references indexed in Scilit:
- Arrangement of high molecular weight associated proteins on purified mammalian brain microtubules.The Journal of cell biology, 1977
- Characterization of a 20S component in tubulin from mammalian brainBiochemistry, 1976
- Quantitative electron microscopy of microtubule assembly in vitroJournal of Molecular Biology, 1975
- Magnesium-induced self-association of calf brain tubulin. I. StoichiometryBiochemistry, 1975
- Ionic and nucleotide requirements for microtubule polymerization in vitroBiochemistry, 1975
- The mechanism of microtubule assembly in vitroJournal of Supramolecular Structure, 1974
- Assembly of microtubules from preformed, ring‐shaped protofilaments and 6‐s tubulinJournal of Supramolecular Structure, 1974
- The role of ring aggregates and other structures in the assembly of microtubulesJournal of Supramolecular Structure, 1974
- Microtubule Formation in vitro in Solutions Containing Low Calcium ConcentrationsScience, 1972
- The lattice spacing of crystalline catalase as an internal standard of length in electron microscopyJournal of Ultrastructure Research, 1968