Molecular and functional characteristics of MAP-2a: Ability of MAP-2a versus MAP-2b to induce stable microtubules in COS cells

Nellie Kalcheva, Julia M. Rockwood, Yvonne Kress, Ari Steiner, Bridget Shafit-Zagardo

Research output: Contribution to journalArticle

27 Scopus citations


Microtubule-associated protein-2 (MAP-2) is a prominent cytoskeletal protein in the mammalian nervous system. Two high-molecular-weight (HMW) MAP- 2 isoforms, MAP-2a and MAP-2b, are developmentally regulated. MAP-2b is expressed through the life of the neuron, while MAP-2a expression coincides with the time of synaptic formation. MAP-2a and MAP-2b differ in size by approximately 10 kD. Attempts to differentiate MAP-2a from MAP-2b led to the identification of additional exons; exons 7A, 8, 13, and 16. The focus of the present study was to define the complete molecular composition of MAP-2a that was prerequisite for investigating the functional characteristic of the MAP- 2a protein. Detailed examination of rat brain mRNA by Northern blot analysis and RT-PCR showed that MAP-2a contains only exon 8 in addition to the exons found in the MAP-2b transcript. Exons 7A, 13, and 16 are not present in the MAP-2a transcript. Antibody generated to exon 8 expressed protein, immunoprecipitated a HMW protein from adult rat brain that co-migrated with MAP-2a and was immunopositire with other MAP-2 antibodies. Comparative transfections of full-length MAP-2a and MAP-2b cDNA into COS-7 cells demonstrated that MAP-2a influenced the microtubule network differently than MAP-2b by inducing rapid and stable microtubule bundle formation even in the presence of nocodazole.

Original languageEnglish (US)
Pages (from-to)272-285
Number of pages14
JournalCell Motility and the Cytoskeleton
Issue number3
StatePublished - Jul 15 1998



  • Acetylated tubulin
  • MAP-2 isoforms
  • MAP-2a
  • MAP-2b
  • Microtubule bundling
  • Microtubules
  • Nocodazole
  • Transient transfections

ASJC Scopus subject areas

  • Structural Biology
  • Cell Biology

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