Sequence determinants of a microtubule tip localization signal (MtLS)

J Biol Chem. 2012 Aug 17;287(34):28227-42. doi: 10.1074/jbc.M112.373928. Epub 2012 Jun 13.


Microtubule plus-end-tracking proteins (+TIPs) specifically localize to the growing plus-ends of microtubules to regulate microtubule dynamics and functions. A large group of +TIPs contain a short linear motif, SXIP, which is essential for them to bind to end-binding proteins (EBs) and target microtubule ends. The SXIP sequence site thus acts as a widespread microtubule tip localization signal (MtLS). Here we have analyzed the sequence-function relationship of a canonical MtLS. Using synthetic peptide arrays on membrane supports, we identified the residue preferences at each amino acid position of the SXIP motif and its surrounding sequence with respect to EB binding. We further developed an assay based on fluorescence polarization to assess the mechanism of the EB-SXIP interaction and to correlate EB binding and microtubule tip tracking of MtLS sequences from different +TIPs. Finally, we investigated the role of phosphorylation in regulating the EB-SXIP interaction. Together, our results define the sequence determinants of a canonical MtLS and provide the experimental data for bioinformatics approaches to carry out genome-wide predictions of novel +TIPs in multiple organisms.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Arabidopsis / chemistry
  • Arabidopsis / genetics
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / chemistry
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Humans
  • Microtubule Proteins / chemistry
  • Microtubule Proteins / genetics
  • Microtubule Proteins / metabolism*
  • Microtubules / chemistry
  • Microtubules / genetics
  • Microtubules / metabolism*
  • Protein Array Analysis
  • Protein Binding
  • Protein Sorting Signals / physiology*
  • Schizosaccharomyces / chemistry
  • Schizosaccharomyces / genetics
  • Schizosaccharomyces / metabolism*
  • Schizosaccharomyces pombe Proteins / chemistry
  • Schizosaccharomyces pombe Proteins / genetics
  • Schizosaccharomyces pombe Proteins / metabolism*


  • Arabidopsis Proteins
  • Microtubule Proteins
  • Protein Sorting Signals
  • Schizosaccharomyces pombe Proteins