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Truncated form of tenascin-X, XB-S, interacts with mitotic motor kinesin Eg5

Toshiya Endo1, Hiroyoshi Ariga, Ken-ichi Matsumoto

  • 1Graduate School of Life Science, Hokkaido University, Kita-ku, Sapporo 060-0812, Japan.

Molecular and Cellular Biochemistry
|August 6, 2008
PubMed

Insights

The truncated tenascin-X (XB-S) protein interacts with mitotic kinesin Eg5. This suggests XB-S may play a role in Eg5 function during cell division.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Biochemistry

Background:

  • The tenascin-X (TNXB) protein is involved in extracellular matrix organization and cell adhesion.
  • XB-S is an amino-terminal-truncated form of tenascin-X, but its in vivo functions remain largely uncharacterized.
  • Understanding the interactions of XB-S is crucial for elucidating its biological roles.

Purpose of the Study:

  • To identify proteins that bind to XB-S in vivo.
  • To investigate the functional relationship between XB-S and its binding partners.
  • To explore the potential role of XB-S in cell division.

Main Methods:

  • Transient expression of FLAG-tagged XB-S in 293T cells.
  • Immunoprecipitation using an anti-FLAG antibody to isolate XB-S-associated proteins.
  • Mass spectrometric analysis to identify co-purified proteins.
  • Co-localization studies using immunofluorescence microscopy.
  • In vitro binding assays using glutathione S-transferase (GST) fusion proteins and in vitro translated Eg5.

Main Results:

  • Mitotic motor kinesin Eg5 was identified as an XB-S-binding protein.
  • XB-S and Eg5 co-localized in the cytoplasm during interphase and mitosis.
  • XB-S did not localize to mitotic spindle microtubules, unlike Eg5.
  • In vitro assays confirmed direct binding between XB-S and Eg5, with the binding site located in Eg5's motor domain.
  • XB-S expression profile paralleled Eg5 expression during the cell cycle.

Conclusions:

  • XB-S directly interacts with the mitotic motor kinesin Eg5.
  • The interaction suggests a potential role for XB-S in regulating Eg5 function during mitosis.
  • Further research is warranted to elucidate the precise mechanism of XB-S involvement in Eg5-mediated processes.

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