Abstract
G12 class heterotrimeric G proteins stimulate RhoA activation by RGS-RhoGEFs. However, p115RhoGEF is a GTPase Activating Protein (GAP) toward Galpha13, whereas PDZRhoGEF is not. We have characterized the interaction between the PDZRhoGEF rgRGS domain (PRG-rgRGS) and the alpha subunit of G13 and have determined crystal structures of their complexes in both the inactive state bound to GDP and the active states bound to GDP*AlF (transition state) and GTPgammaS (Michaelis complex). PRG-rgRGS interacts extensively with the helical domain and the effector-binding sites on Galpha13 through contacts that are largely conserved in all three nucleotide-bound states, although PRG-rgRGS has highest affinity to the Michaelis complex. An acidic motif in the N terminus of PRG-rgRGS occupies the GAP binding site of Galpha13 and is flexible in the GDP*AlF complex but well ordered in the GTPgammaS complex. Replacement of key residues in this motif with their counterparts in p115RhoGEF confers GAP activity.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Animals
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GTP-Binding Protein alpha Subunits, G12-G13 / chemistry*
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GTP-Binding Protein alpha Subunits, G12-G13 / metabolism*
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GTPase-Activating Proteins / genetics
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GTPase-Activating Proteins / metabolism
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Guanine Nucleotide Exchange Factors / chemistry*
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Guanine Nucleotide Exchange Factors / genetics
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Guanine Nucleotide Exchange Factors / metabolism*
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Guanosine 5'-O-(3-Thiotriphosphate) / metabolism
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Mice
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Models, Molecular
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Molecular Sequence Data
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Protein Binding
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Protein Interaction Domains and Motifs
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Protein Structure, Quaternary
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Protein Structure, Tertiary
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RGS Proteins / chemistry
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Rats
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Sequence Homology, Amino Acid
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Substrate Specificity / genetics
Substances
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GTPase-Activating Proteins
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Guanine Nucleotide Exchange Factors
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PDZ-RhoGEF, rat
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RGS Proteins
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Guanosine 5'-O-(3-Thiotriphosphate)
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GTP-Binding Protein alpha Subunits, G12-G13
Associated data
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PDB/3CX6
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PDB/3CX7
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PDB/3CX8