Association of Arabidopsis type-II ROPs with the plasma membrane requires a conserved C-terminal sequence motif and a proximal polybasic domain
Article first published online: 18 MAY 2006
The Plant Journal
Volume 46, Issue 6, pages 934–947, June 2006
How to Cite
Lavy, M. and Yalovsky, S. (2006), Association of Arabidopsis type-II ROPs with the plasma membrane requires a conserved C-terminal sequence motif and a proximal polybasic domain. The Plant Journal, 46: 934–947. doi: 10.1111/j.1365-313X.2006.02749.x
- Issue published online: 18 MAY 2006
- Article first published online: 18 MAY 2006
- Received 18 January 2006; revised 26 February 2006; accepted 28 February 2006.
- membrane association;
Plant ROPs (or RACs) are soluble Ras-related small GTPases that are attached to cell membranes by virtue of the post-translational lipid modifications of prenylation and S-acylation. ROPs (RACs) are subdivided into two major subgroups called type-I and type-II. Whereas type-I ROPs terminate with a conserved CaaL box and undergo prenylation, type-II ROPs undergo S-acylation on two or three C-terminal cysteines. In the present work we determined the sequence requirement for association of Arabidopsis type-II ROPs with the plasma membrane. We identified a conserved sequence motif, designated the GC-CG box, in which the modified cysteines are flanked by glycines. The GC-CG box cysteines are separated by five to six mostly non-polar residues. Deletion of this sequence or the introduction of mutations that change its nature disrupted the association of ROPs with the membrane. Mutations that changed the GC-CG box glycines to alanines also interfered with membrane association. Deletion of a polybasic domain proximal to the GC-CG box disrupted the plasma membrane association of AtROP10. A green fluorescent protein fusion protein containing the C-terminal 25 residues of AtROP10, including its polybasic domain and GC-CG box, was primarily associated with the plasma membrane but a similar fusion protein lacking the polybasic domain was exclusively localized in the soluble fraction. These data provide evidence for the minimal sequence required for plasma membrane association of type-II ROPs in Arabidopsis and other plant species.