Abstract
Signaling through G proteins normally involves conformational switching between GTP- and GDP-bound states. Several Rho GTPases are also regulated by RhoGDI binding and sequestering in the cytosol. Rnd proteins are atypical constitutively GTP-bound Rho proteins, whose regulation remains elusive. Here, we report a high-affinity 14-3-3-binding site at the C terminus of Rnd3 consisting of both the Cys241-farnesyl moiety and a Rho-associated coiled coil containing protein kinase (ROCK)-dependent Ser240 phosphorylation site. 14-3-3 binding to Rnd3 also involves phosphorylation of Ser218 by ROCK and/or Ser210 by protein kinase C (PKC). The crystal structure of a phosphorylated, farnesylated Rnd3 peptide with 14-3-3 reveals a hydrophobic groove in 14-3-3 proteins accommodating the farnesyl moiety. Functionally, 14-3-3 inhibits Rnd3-induced cell rounding by translocating it from the plasma membrane to the cytosol. Rnd1, Rnd2, and geranylgeranylated Rap1A interact similarly with 14-3-3. In contrast to the canonical GTP/GDP switch that regulates most Ras superfamily members, our results reveal an unprecedented mechanism for G protein inhibition by 14-3-3 proteins.
Original language | English |
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Pages (from-to) | 640-53 |
Number of pages | 14 |
Journal | Cell |
Volume | 153 |
Issue number | 3 |
DOIs | |
Publication status | Published - 25 Apr 2013 |
Keywords
- 14-3-3 Proteins
- Amino Acid Sequence
- Animals
- COS Cells
- Cell Membrane
- Cercopithecus aethiops
- Crystallography, X-Ray
- Cytosol
- Humans
- Models, Molecular
- Molecular Sequence Data
- Phosphorylation
- Prenylation
- Protein Interaction Domains and Motifs
- rho GTP-Binding Proteins
- Journal Article
- Research Support, Non-U.S. Gov't