The C-terminal polylysine region and methylation of K-Ras are critical for the interaction between K-Ras and microtubules.

Journal Article (Journal Article)

After synthesis in the cytosol, Ras proteins must be targeted to the inner leaflet of the plasma membrane for biological activity. This targeting requires a series of C-terminal posttranslational modifications initiated by the addition of an isoprenoid lipid in a process termed prenylation. A search for factors involved in the intracellular trafficking of Ras has identified a specific and prenylation-dependent interaction between tubulin/microtubules and K-Ras. In this study, we examined the structural requirements for this interaction between K-Ras and microtubules. By using a series of chimeras in which regions of the C terminus of K-Ras were replaced with those of Ha-Ras and vice versa, we found that the polylysine region of K-Ras located immediately upstream of the prenylation site is required for binding of K-Ras to microtubules. Studies in intact cells confirmed the importance of the K-Ras polylysine region for microtubule binding, as deletion or replacement of this region resulted in loss of paclitaxel-induced mislocalization of a fluorescent K-Ras fusion protein. The additional modifications in the prenyl protein processing pathway also affected the interaction of K-Ras with microtubules. Removal of the three C-terminal amino acids of farnesylated K-Ras with the specific endoprotease Rce1p abolished its binding to microtubules. Interestingly, however, methylation of the C-terminal prenylcysteine restored binding. Consistent with these results, localization of the fluorescent K-Ras fusion protein remained paclitaxel-sensitive in cells lacking Rce1, whereas no paclitaxel effect was observed in cells lacking the methyltransferase. These studies show that the polylysine region of K-Ras is critical for its interaction with microtubules and provide the first evidence for a functional consequence of Ras C-terminal proteolysis and methylation.

Full Text

Duke Authors

Cited Authors

  • Chen, Z; Otto, JC; Bergo, MO; Young, SG; Casey, PJ

Published Date

  • December 29, 2000

Published In

Volume / Issue

  • 275 / 52

Start / End Page

  • 41251 - 41257

PubMed ID

  • 11007785

International Standard Serial Number (ISSN)

  • 0021-9258

Digital Object Identifier (DOI)

  • 10.1074/jbc.M006687200


  • eng

Conference Location

  • United States