Identification of a novel family of 70 kDa microtubule-associated proteins in Arabidopsis cells

Plant J. 2005 May;42(4):547-55. doi: 10.1111/j.1365-313X.2005.02393.x.


Most plant microtubule-associated proteins (MAPs) have homologues across the phylogenetic spectrum. To find potential plant-specific MAPs that will have evaded bioinformatic searches we devised a low stringency method for isolating proteins from an Arabidopsis cell suspension on endogenous taxol-microtubules. By tryptic peptide mass fingerprinting we identified 55 proteins that were enriched on taxol-microtubules. Amongst a range of known MAPs, such as kinesins, MAP65 isoforms and MOR1, we detected 'unknown' 70 kDa proteins that belong to a family of five closely related Arabidopsis proteins having no known homologues amongst non-plant organisms. To verify that AtMAP70-1 associates with microtubules in vivo, it was expressed as a GFP fusion. This confirmed that the protein decorates all four microtubule arrays in both transiently infected Arabidopsis and stably transformed tobacco BY-2 suspension cells. Microtubule-directed drugs perturbed the localization of AtMAP70-1 but cytochalasin D did not. AtMAP70-1 contains four predicted coiled-coil domains and truncation studies identified a central domain that targets the fusion protein to microtubules in vivo. This study therefore introduces a novel family of plant-specific proteins that interact with microtubules.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Arabidopsis / chemistry*
  • Arabidopsis Proteins / chemistry
  • Arabidopsis Proteins / isolation & purification*
  • Gene Expression Regulation, Plant
  • Microtubule-Associated Proteins / chemistry
  • Microtubule-Associated Proteins / isolation & purification*
  • Molecular Sequence Data
  • Sequence Alignment
  • Sequence Homology, Amino Acid


  • Arabidopsis Proteins
  • Microtubule-Associated Proteins