Contrasting roles of tau and microtubule-associated protein 2 in the vinblastine-induced aggregation of brain tubulin

R. F. Luduena, A. Fellous, L. McManus, M. A. Jordan, J. Nunez

Research output: Contribution to journalArticle

41 Scopus citations

Abstract

Two different proteins, tau and microtubule-associated protein 2 (MAP 2), are able to stimulated tubulin polymerization into microtubules in vitro, but it is not certain if both proteins act by the same mechanism. We have examined the effects of tau and MAP 2 on the vinblastine-induced polymerization of tubulin into spiral filaments. In the presence of tau, vinblastine induced extensive aggregation of tubulin as shown by a large increase in turbidity. The increase in turbidity was accompanied by the formation of large numbers of spirals composed of a filament 40-60 Å in diameter. The rate and extent of this aggregation into spirals were dependent on the concentrations of tubulin, tau, and vinblastine. Unlike normal microtubule assembly, this type of aggregation was not inhibited by colchicine or podophyllotoxin. In contrast, MAP 2, even at high concentrations, was less effective than tau at promoting the vinblastine-induced increase in turbidity of tubulin. In fact, MAP 2 strongly inhibited the effect of tau. These results indicate that tau and MAP 2 interact differently with the tubulin molecule in the presence of vinblastine and suggest that the two proteins may play different roles in regulating or promoting microtubule assembly. Vinblastine may thus be a useful probe in analyzing the modes of interactions of tau and MAP 2 with tubulin.

Original languageEnglish (US)
Pages (from-to)12890-12898
Number of pages9
JournalJournal of Biological Chemistry
Volume259
Issue number20
StatePublished - 1984

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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