Xanthine nucleotide-specific G-protein alpha-subunits: a novel approach for the analysis of G-protein-mediated signal transduction.
Pro- and eukaryotic cells express multiple GTP-binding proteins that play crucial roles in signal transduction. GTP-binding proteins possess a highly conserved NKX D motif critically involved in guanine binding. In order to selectively activate a defined GTP-binding protein, base-specificity can be switched from guanine to xanthine by mutating the conserved aspartate into asparagine (D/N-mutation). This approach was very successful at elucidating the function of structurally diverse GTP-binding proteins in complex systems. However, attempts to generate functional xanthine nucleotide-specific alpha-subunits of heterotrimeric GTP-binding proteins (G-proteins) met more difficulties. Recent studies have shown that a sufficiently high GDP-affinity is critical for functional expression of xanthine nucleotide-selective G-protein mutants. Moreover, xanthosine 5'-[gamma-thio]triphosphate and xanthosine 5'-[gamma, beta-imido]triphosphate are not functionally equivalent activators of D/N-G-protein mutants. We are now in the position to exploit xanthine nucleotide-specific G-proteins to dissect signaling pathways activated by a given G-protein in complex systems.
Gille
Andreas
A
Department of Pharmacology and Toxicology, The University of Kansas, 1251 Wescoe Hall Drive, Malott Hall, Room 5064, Lawrence, KS 66045-7582, USA.
Seifert
Roland
R
D000818:Animals; D044385:GTP-Binding Protein alpha Subunits / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D019204:GTP-Binding Proteins / Q000502:physiology*; D009154:Mutation; D011685:Purine Nucleotides / Q000378:metabolism*; D015398:Signal Transduction; D014970:Xanthines / Q000378:metabolism*
D044385:GTP-Binding Protein alpha Subunits; D011685:Purine Nucleotides; D014970:Xanthines; D019204:GTP-Binding Proteins