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Comparing the Affinity of GTPase-binding Proteins using Competition Assays
Published on: October 8, 2015
Molecular basis for the substrate specificity of plant guanine nucleotide exchange factors for ROP
1Max Planck Institute of Molecular Physiology, Structural Biology Department, Dortmund, Germany.
Abstract:
Plant G proteins of the ROP/RAC family regulate cellular processes including cytoskeletal rearrangement in polar growth. Activation of the ROP molecular switch is triggered by guanine nucleotide exchange factors. Plant-specific RopGEFs are exclusively active on ROPs despite their high homology to animal Rho proteins. Based on a sequence comparison of ROPs vs. animal Rho proteins together with structural data on distinct ROPs, we identified unique substrate determinants of RopGEF specificity by mutational analysis: asparagine 68 next to switch II, arginine 76 of a putative phosphorylation motif and the Rho insert are essential for substrate recognition by RopGEFs. These data also provide first evidence for a function of the Rho insert in interactions with GEFs.
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