Guanosinetriphosphatase activity of tubulin associated with microtubule assembly.

Journal Article

Tubulin, purified by cycles of assembly followed by phosphocellulose chromatography, exhibits a characteristic GTPase activity that is polymerization dependent and can be attributed to the tubulin itself. This activity has been observed, in a standard reassembly buffer containing low Mg2+, under three conditions that induce microtubule assembly: in the presence of microtubule-associated proteins, in the presence of DEAE-dextran, or after addition of high Mg2+ and glycerol. The phosphocellulose-purified tubulin showed no GTPase activity under the following nonpolymerizing conditions: in buffer with low Mg2+ in the absence of microtubule-associated proteins or DEAE-dextran, in buffer with high Mg2+ and glycerol at tubulin concentrations below the critical concentration, or when microtubule assembly was inhibited by vinblastine. Colchicine, on the other hand, while blocking microtubule assembly, induced a significant GTPase activity in the phosphocellulose-purified tubulin. During the process of assembly, GTP appears to be hydrolyzed as a free tubulin dimer polymerizes into a microtubule. A constant GTPase activity when polymerization equilibrium is reached apparently reflects the cyclic polymerization-depolymerization of tubulin dimers at the ends of the microtubules.

Full Text

Duke Authors

Cited Authors

  • David-Pfeuty, T; Erickson, HP; Pantaloni, D

Published Date

  • December 1977

Published In

Volume / Issue

  • 74 / 12

Start / End Page

  • 5372 - 5376

PubMed ID

  • 202954

International Standard Serial Number (ISSN)

  • 0027-8424

Language

  • eng

Conference Location

  • United States