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Dynamics of the microtubule oscillator: role of nucleotides and tubulin‐MAP interactions.
Author(s) -
Mandelkow E. M.,
Lange G.,
Jagla A.,
Spann U.,
Mandelkow E.
Publication year - 1988
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1988.tb02821.x
Subject(s) - microtubule , tubulin , gtp' , biophysics , nucleotide , biology , guanosine diphosphate , microtubule nucleation , intracellular , biochemistry , crystallography , guanosine triphosphate , microbiology and biotechnology , chemistry , enzyme , centrosome , cell , cell cycle , gene
Microtubules can be induced to perform synchronous and periodic cycles of assembly and disassembly at constant temperature. The process depends on GTP hydrolysis. Time‐resolved X‐ray scattering using synchrotron radiation shows a cyclic interconversion of tubulin subunits, microtubules and oligomers (= short protofilament fragments). Oscillations are correlated with conditions that stabilize polymers and destabilize oligomers, and others of opposite effect. Microtubule stabilizers include GTP, Mg2+ or microtubule‐associated proteins (MAPs), destabilizers include GDP or elevated ionic strength. K+ at intracellular concentrations noticeably increases the stability of tubulin‐MAP oligomers, in contrast to Na+. ATP and the non‐hydrolyzable analogue AMP‐PNP enhance oscillations by mechanisms that are not directly linked to the role of nucleotide hydrolysis in assembly. We propose a mechanism of oscillations that include oligomers as microtubule disassembly products which transiently lock the protein in an unpolymerizable state; this may point to a role of oligomers in controlling microtubule assembly cycles in cells.