Mg X ATP2-dependent interaction of the inhibitor protein of the cAMP-dependent protein kinase with the catalytic subunit.

摘要: The interaction between the inhibitor protein and catalytic subunit of cAMP-dependent kinase has been investigated by steady state kinetics an assessment requirement this for ATP. By analysis tightly bound inhibitors, inhibition was shown to be competitive versus peptide substrate uncompetitive Mg X ATP2-. This, together with observations Gronot et al. (Gronot, J., Mildvan, A.S., Bramson, H. N., Thomas, Kaiser, E.T. (1981) Biochemistry 20, 602-610) those given in accompanying paper (Whitehouse, S., Feramisco, J.R., Casnellie, J.E., Krebs, E.G., Walsh, D.A. (1983) J. Biol. Chem. 258, 3693-3701), would indicate that probable reaction mechanism is ordered nucleotide binding first blocks catalysis subunit-Mg ATP complex. Ki at saturating zero 0.49 nM. Multiple presence 5'-adenylimidodiphosphate (AMP PNP) indicates does not interact a subunit-AMP PNP protein-catalytic also demonstrated direct measurements observation efficiency increased preincubation protein, subunit, absence substrate. either measurement, exhibit apparent Kd 20 approximately 60 nM ATP; value two orders magnitude higher than affinity alone. This high (in inhibitor) require there specific site on some moiety but may simply reflection formation complex resultant displacement equilibrium kinase.