Interaction of nucleoside diphosphate kinase B with heterotrimeric G protein betagamma dimers: consequences on G protein activation and stability.
It is generally accepted that G protein coupled receptors (GPCR) activate heterotrimeric G proteins by inducing a GDP/GTP exchange at the G protein alpha subunit. In addition, the transfer of high energetic phosphate by nucleoside diphosphate kinase (NDPK) and/or the beta subunit of G proteins (Gbeta) can induce G protein activation. Recent evidence suggests that the NDPK isoform B (NDPK B) forms a complex with Gbetagamma dimers. In this complex, NDPK B acts as a protein histidine kinase phosphorylating Gbeta at histidine residue 266 (His266). The high energetic phosphoamidate bond on His266 allows for a phosphate transfer specifically onto GDP and thus local formation of GTP, which binds to and thereby activates the respective G protein alpha subunit. Apparently, this process occurs independent of the classical GPCR-induced GDP/GTP exchange at least for members of the G(s) and G(i) subfamilies of heterotrimeric G proteins. By using a mutant of Gbeta(1) in which His266 was replaced by Leu, it was recently demonstrated that NDPK B/Gbetagamma-mediated G(s) activation contributes by about 50% to basal cAMP formation and contractility in rat cardiac myocytes. Besides its apparent role in G protein activation, the complex formation of NDPK B with Gbetagamma dimers might be essential for G protein stability. Depletion of either the NDPK B orthologue or Gbeta(1) isoforms in zebrafish embryos led to a similar phenotype displaying contractile dysfunction in the heart accompanied by a complete loss of heterotrimeric G protein expression. In conclusion, the interaction of NDKP B with Gbetagamma dimers might play an important role in signal transduction, and alterations in this novel pathway might be of pathophysiological importance.
Wieland
Thomas
T
Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Medizinische Fakultät Mannheim, Universität Heidelberg, Maybachstrasse 14, D-68169 Mannheim, Germany. thomas.wieland@pharmtox.uni-heidelberg.de
D000818:Animals; D019281:Dimerization; D044387:GTP-Binding Protein beta Subunits / Q000737:chemistry / Q000378:metabolism*; D044388:GTP-Binding Protein gamma Subunits / Q000737:chemistry / Q000378:metabolism*; D006333:Heart Failure / Q000378:metabolism; D006801:Humans; D008954:Models, Biological; D054778:NM23 Nucleoside Diphosphate Kinases; D009701:Nucleoside-Diphosphate Kinase / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism
D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D054778:NM23 Nucleoside Diphosphate Kinases; D043562:Receptors, G-Protein-Coupled; C517940:NME2 protein, human; D009701:Nucleoside-Diphosphate Kinase