Assembly of chick brain MAP2-tubulin microtubule protein. Characterization of the protein and the MAP2-dependent addition of tubulin dimers.
The principle proteins present in twice-cycled chick brain microtubule protein were characterized. The protein consists of a stoichiometric mixture of MAP2 and tubulin, together with a number of minor components. Its composition remains unaltered after a third cycle of assembly in a buffer supplemented with 67 mM-NaCl, with the exception of the phosphorylation of MAP2 to a low level (congruent to 1 mol.mol-1). The inclusion of 67 mM-NaCl dissociates the MAP2-tubulin oligomers, and restricts the assembly to the MAP2-dependent addition and loss of tubulin dimers, such that the assembly kinetics approximate to a simple pseudo-first-order reaction. The assembled microtubules exhibit dynamic instability, with no evidence for end-to-end annealing.
Burns
R G
RG
Biophysics Section, Blackett Laboratory, Imperial College of Science, Technology and Medicine, London, U.K.
D000818:Animals; D001921:Brain / Q000378:metabolism*; D002645:Chickens; D002850:Chromatography, Gel; D006160:Guanosine Triphosphate / Q000378:metabolism; D007700:Kinetics; D046911:Macromolecular Substances; D008868:Microtubule Proteins / Q000302:isolation & purification / Q000378:metabolism*; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism* / Q000648:ultrastructure; D010766:Phosphorylation; D014404:Tubulin / Q000378:metabolism*
D046911:Macromolecular Substances; D008868:Microtubule Proteins; D008869:Microtubule-Associated Proteins; D014404:Tubulin; D006160:Guanosine Triphosphate