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A specific domain of Gialpha required for the transactivation of Gialpha by tubulin is implicated in the organization of cellular microtubules.

Publication ,  Journal Article
Chen, N-F; Yu, J-Z; Skiba, NP; Hamm, HE; Rasenick, MM
Published in: J Biol Chem
April 25, 2003

G(s)alpha, G(i)alpha(1), and G(q)alpha subunits bind tubulin with high affinity, whereas transducin (G(t)alpha) does not. The interaction between tubulin and Galpha, which also involves the direct transfer of GTP from tubulin to Galpha (transactivation), is not yet fully understood. This study, using chimeras of G(i)alpha and G(t)alpha, showed that the G(i)alpha (215-295) segment converted G(t)alpha to bind to tubulin and this chimera (chimera 1) could be transactivated by tubulin. Insertion of G(t)alpha (237-270) into chimera 1 to form chimera 2 resulted in a protein that, like G(t)alpha, did not bind tubulin. Thus, it was thought that the G(i)alpha (237-270) domain was essential to modulate the binding of G(i)alpha(1) to tubulin. Surprisingly, when domain (237-270) of G(i)alpha was replaced by G(t)alpha (237-270) to form chimera 3, the chimera bound to tubulin with a similar affinity (K(D) congruent with 120 nm) as wild-type G(i)alpha(1). However, even though chimera 3 displayed normal GTP binding, it was not transactivated by GTP-tubulin. Furthermore, when these chimeras were expressed in COS-1 cells, cellular processes in cells overexpressing G(i)alpha(1) or chimera 1 were more abundant and longer than those in native cells. Galpha was seen throughout the length of the process. Morphology of cells expressing chimera 2 was identical to controls. Consistent with the role of Chimera 3 as a "dominant negative" Galpha, cells transfected with chimera 3 had only few truncated processes. This study demonstrates that although G(i)alpha (237-270) is not obligatory for the binding of G(i)alpha to tubulin, it is crucial for the transactivation of Galpha by tubulin. These results also suggest that the transactivation of Galpha by tubulin may play an important role in modulating microtubule organization and cell morphology.

Duke Scholars

Published In

J Biol Chem

DOI

ISSN

0021-9258

Publication Date

April 25, 2003

Volume

278

Issue

17

Start / End Page

15285 / 15290

Location

United States

Related Subject Headings

  • Tubulin
  • Transfection
  • Transducin
  • Transcriptional Activation
  • Recombinant Fusion Proteins
  • Protein Subunits
  • Protein Structure, Tertiary
  • Protein Binding
  • Microtubules
  • Humans
 

Citation

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MLA
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Chen, N.-F., Yu, J.-Z., Skiba, N. P., Hamm, H. E., & Rasenick, M. M. (2003). A specific domain of Gialpha required for the transactivation of Gialpha by tubulin is implicated in the organization of cellular microtubules. J Biol Chem, 278(17), 15285–15290. https://doi.org/10.1074/jbc.M300841200
Chen, Ning-Fang, Jiang-Zhou Yu, Nikolai P. Skiba, Heidi E. Hamm, and Mark M. Rasenick. “A specific domain of Gialpha required for the transactivation of Gialpha by tubulin is implicated in the organization of cellular microtubules.J Biol Chem 278, no. 17 (April 25, 2003): 15285–90. https://doi.org/10.1074/jbc.M300841200.
Chen, Ning-Fang, et al. “A specific domain of Gialpha required for the transactivation of Gialpha by tubulin is implicated in the organization of cellular microtubules.J Biol Chem, vol. 278, no. 17, Apr. 2003, pp. 15285–90. Pubmed, doi:10.1074/jbc.M300841200.
Chen N-F, Yu J-Z, Skiba NP, Hamm HE, Rasenick MM. A specific domain of Gialpha required for the transactivation of Gialpha by tubulin is implicated in the organization of cellular microtubules. J Biol Chem. 2003 Apr 25;278(17):15285–15290.

Published In

J Biol Chem

DOI

ISSN

0021-9258

Publication Date

April 25, 2003

Volume

278

Issue

17

Start / End Page

15285 / 15290

Location

United States

Related Subject Headings

  • Tubulin
  • Transfection
  • Transducin
  • Transcriptional Activation
  • Recombinant Fusion Proteins
  • Protein Subunits
  • Protein Structure, Tertiary
  • Protein Binding
  • Microtubules
  • Humans