PKB/Akt interacts with inosine-5' monophosphate dehydrogenase through its pleckstrin homology domain.
The pleckstrin homology (PH) domain of the protooncogenic serine/threonine protein kinase PKB/Akt can bind phosphoinositides. A yeast-based two-hybrid system was employed which identified inosine-5' monophosphate dehydrogenase (IMPDH) type II as specifically interacting with PKB/Akts PH domain. IMPDH catalyzes the rate-limiting step of de novo guanosine-triphosphate (GTP) biosynthesis. Using purified fusion proteins, PKB/Akts PH domain and IMPDH associated in vitro and this association moderately activated IMPDH. Purified PKB/Akt also associated with IMPDH in vitro. We could specifically pull-down PKB/Akt or IMPDH from mammalian cell lysates using glutathione-S-transferase (GST)-IMPDH or GST-PH domain fusion proteins, respectively. Additionally, PKB/Akt and IMPDH could be co-immunoprecipitated from COS cell lysates and active PKB/Akt could phosphorylate IMPDH in vitro. These results implicate PKB/Akt in the regulation of GTP biosynthesis through its interaction with IMPDH, which is involved in providing the GTP pool used by signal transducing G-proteins.
Friedrich Miescher-Institut, Basel, Switzerland.
E
E
Ingley
B A
BA
Hemmings
D000818:Animals; D001665:Binding Sites; D001798:Blood Proteins / Q000737:chemistry*; D002460:Cell Line; D004789:Enzyme Activation; D019204:GTP-Binding Proteins / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D007168:IMP Dehydrogenase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D010750:Phosphoproteins / Q000737:chemistry*; D010766:Phosphorylation; D011233:Precipitin Tests; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D017384:Sequence Deletion / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D014162:Transfection; D020798:Two-Hybrid System Techniques
D001798:Blood Proteins; D010750:Phosphoproteins; D011518:Proto-Oncogene Proteins; C039077:platelet protein P47; D006160:Guanosine Triphosphate; D007168:IMP Dehydrogenase; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D019204:GTP-Binding Proteins