18 kDa microtubule-associated protein: identification as a new light chain (LC-3) of microtubule-associated protein 1 (MAP-1)

Sergei A. Kuznetsov, Vladimir I. Gelfand*

*Corresponding author for this work

Research output: Contribution to journalArticle

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SDS gel electrophoresis of microtubule proteins obtained from bovine brain by polymerization cycles revealed a new protein of 18 kDa. This protein was copolymerized with tubulin and its stoichiometry to tubulin remained constant for at least 5 cycles of assembly. Moreover, this protein remained bound to microtubules stabilized with 10 μM taxol and pelleted through a 4 M glycerol cushion. The same 18 kDa protein was found in a purified preparation of the high molecular mass microtubule-associated protein 1 (MAP-1). The 18 kDa protein copurified with the MAP-1 heavy chains during column chromatography on phosphocellulose, DEAE-cellulose, hydroxyapatite and Bio-Gel A-15m. Incubation of the MAP-1 preparation with a mouse monoclonal antibody to the light chain 1 (LC-1) of MAP-1 and with a second precipitating antibody (a rabbit antibody to mouse IgG) immunoprecipitated from the solution all the known components of MAP-1 (heavy chains, LC-1, LC-2), as well as the 18 kDa protein. Immunoblotting showed, however, that this antibody does not interact directly with the 18 kDa protein. These results indicate that the 18 kDa protein forms a complex with all other components of MAP-1. This polypeptide, therefore, is a new light chain (LC-3) of M AP-1.

Original languageEnglish (US)
Pages (from-to)145-148
Number of pages4
JournalFEBS Letters
Issue number1
StatePublished - Feb 9 1987



  • Immunoprecipitation
  • Microtubule
  • Microtubule-associated protein 1

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology

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