Interaction between Pleckstrin Homology Domains and G Protein βγ-Subunits : Analyses of Kinetic Parameters by a Biosensor-Based Method

概要

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Pleckstrin homology (PH) domains, comprised of rather weakly conserved sequences of about 100 amino acid residues, are a protein motif found in many signaling and cytoskeletal proteins. PH domains have been shown to bind to the βγ subunits of heterotrimeric GTP-binding proteins (G_<βγ>), but the affinity of PH domains for G_<βγ> has not been quantitatively estimated in detail. To characterize the nature of the interaction between PH domains and G_<βγ>, its kinetic parameters were analyzed using a BIAcore^<TM> instrument. All PH domains tested (PH domains of ras-specific guanine nucleotide exchange factor (ras-GRF), phospholipase (PLC) γ1,and Son of sevenless protein (Sos)) appeared to bind to G_<β1γ2> with affinity constants K_D of 0.108,0.318,and 0.208 μM, respectively. The binding of PH domains to G_<βγ> was inhibited by preincubation of G_<βγ> with the GDP-bound but not the GTP-bound form of Gi_α. This study showed a high affinity interaction between PH domains and G_<βγ> and suggests a potential role of PH domains in G_<βγ>-mediated signal transduction in intact cells.
公益社団法人日本薬学会の論文
1999-03-15