Phosphoryl exchange is involved in the mechanism of the insulin receptor kinase.
The cytoplasmic kinase domain of the human insulin receptor (IRKD; M(r) 49 kDa) has been over-expressed in insect cells using the baculovirus expression system. To investigate the kinase mechanism, we have compared the stoichiometry of ADP formation and phosphoryl transfer. After an initial phase of autophosphorylation, ATP is consumed without a stoichiometric increase in incorporated phosphate. During substrate phosphorylation using poly(Glu:Tyr) (4:1) phosphoryl transfer comes close to ATP turnover, which is independent of the presence of the substrate, indicating an increased efficiency (i.e. ATP turnover/phosphate incorporation) of phosphoryl transfer. Autophosphorylation under pulse-chase conditions suggests the existence of a phosphoenzyme intermediate.
al-Hasani
H
H
Diabetes Research Institute Düsseldorf, Germany.
Passlack
W
W
Klein
H W
HW
D000255:Adenosine Triphosphate / Q000378:metabolism; D000266:Adenylyl Imidodiphosphate / Q000494:pharmacology; D000470:Alkaloids / Q000494:pharmacology; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000037:antagonists & inhibitors; D010766:Phosphorylation; D010770:Phosphotransferases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011487:Protein Conformation; D011972:Receptor, Insulin / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D019311:Staurosporine
D000470:Alkaloids; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; D010710:Phosphates; D011994:Recombinant Proteins; D000266:Adenylyl Imidodiphosphate; C027606:L-glutamic acid-L-tyrosine copolymer; D000255:Adenosine Triphosphate; D010770:Phosphotransferases; D011972:Receptor, Insulin; D010744:Phosphoric Monoester Hydrolases; D019311:Staurosporine