2om2
From Proteopedia
Crystal Structure Of Human G[alpha]i1 Bound To The Goloco Motif Of Rgs14
Structural highlights
Function[GNAI1_HUMAN] Guanine nucleotide-binding proteins (G proteins) are involved as modulators or transducers in various transmembrane signaling systems. The G(i) proteins are involved in hormonal regulation of adenylate cyclase: they inhibit the cyclase in response to beta-adrenergic stimuli. The inactive GDP-bound form prevents the association of RGS14 with centrosomes and is required for the translocation of RGS14 from the cytoplasm to the plasma membrane. May play a role in cell division.[1] [2] [RGS14_HUMAN] Acts as a regulator of G protein signaling (RGS). Modulates G protein alpha subunits nucleotide exchange and hydrolysis activities by functioning either as a GTPase-activating protein (GAP), thereby driving G protein alpha subunits into their inactive GDP-bound form, or as a GDP-dissociation inhibitor (GDI). Confers GDI activity on G(i) alpha subunits GNAI1 and GNAI3, but not G(o) alpha subunit GNAO1 and G(i) alpha subunit GNAI2. Confers GAP activity on G(o) alpha subunit GNAI0 and G(i) alpha subunits GNAI2 and GNAI3. May act as a scaffold integrating G protein and Ras/Raf MAPkinase signaling pathways. Inhibits platelet-derived growth factor (PDGF)-stimulated ERK1/ERK2 phosphorylation; a process depending on its interaction with HRAS1 and that is reversed by G(i) alpha subunit GNAI1. Acts as a positive modulator of microtubule polymerisation and spindle organization through a G(i)-alpha-dependent mechanism. Plays a role in cell division. Probably required for the nerve growth factor (NGF)-mediated neurite outgrowth. May be involved in visual memory processing capacity and hippocampal-based learning and memory.[3] [4] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe ability to manipulate protein binding affinities is important for the development of proteins as biosensors, industrial reagents, and therapeutics. We have developed a structure-based method to rationally predict single mutations at protein-protein interfaces that enhance binding affinities. The protocol is based on the premise that increasing buried hydrophobic surface area and/or reducing buried hydrophilic surface area will generally lead to enhanced affinity if large steric clashes are not introduced and buried polar groups are not left without a hydrogen bond partner. The procedure selects affinity enhancing point mutations at the protein-protein interface using three criteria: (1) the mutation must be from a polar amino acid to a non-polar amino acid or from a non-polar amino acid to a larger non-polar amino acid, (2) the free energy of binding as calculated with the Rosetta protein modeling program should be more favorable than the free energy of binding calculated for the wild-type complex and (3) the mutation should not be predicted to significantly destabilize the monomers. The performance of the computational protocol was experimentally tested on two separate protein complexes; Galpha(i1) from the heterotrimeric G-protein system bound to the RGS14 GoLoco motif, and the E2, UbcH7, bound to the E3, E6AP from the ubiquitin pathway. Twelve single-site mutations that were predicted to be stabilizing were synthesized and characterized in the laboratory. Nine of the 12 mutations successfully increased binding affinity with five of these increasing binding by over 1.0 kcal/mol. To further assess our approach we searched the literature for point mutations that pass our criteria and have experimentally determined binding affinities. Of the eight mutations identified, five were accurately predicted to increase binding affinity, further validating the method as a useful tool to increase protein-protein binding affinities. Structure-based protocol for identifying mutations that enhance protein-protein binding affinities.,Sammond DW, Eletr ZM, Purbeck C, Kimple RJ, Siderovski DP, Kuhlman B J Mol Biol. 2007 Aug 31;371(5):1392-404. Epub 2007 Jun 8. PMID:17603074[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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