GTP hydrolysis by tubulin occurs with water oxygen incorporation into inorganic phosphate.
Tubulin assembly was conducted in [18O]H2O and the resulting mixture of GTP, GDP and Pi was examined by 31P-NMR. Two Pi signals, separated by about 0.02 ppm, were observed. By combining this mixture with a solution of Pi containing all five possible 16O and 18O isotopomers of Pi, it was shown that the two signals were due to [16O4]- and [16O3, 18O]Pi. The amount of 18O incorporated into the Pi was that expected if the hydrolysis of GTP during tubulin assembly occurs with cleavage of the gamma-phosphorus-bridge oxygen bond.
Osei
A A
AA
Department of Biochemistry, University of Kansas, Lawrence 66045.
Everett
G W
GW
Himes
R H
RH
D000818:Animals; D002417:Cattle; D055598:Chemical Phenomena; D002621:Chemistry; D006160:Guanosine Triphosphate / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008870:Microtubules / Q000378:metabolism; D010100:Oxygen; D010710:Phosphates / Q000378:metabolism*; D014404:Tubulin / Q000378:metabolism*; D014867:Water
D010710:Phosphates; D014404:Tubulin; D014867:Water; D006160:Guanosine Triphosphate; D010100:Oxygen