NADH oxidase activity of rat liver plasma membrane activated by guanine nucleotides.
The activity of a hormone- and growth-factor-stimulated NADH oxidase of the rat liver plasma membrane responds to guanine nucleotides, but in a manner that differs from that of the classic trimeric and low-molecular-mass monomeric G-proteins. In the absence of added bivalent ions, both GTP and GDP as well as guanosine 5'-[gamma-thio]triphosphate (GTP[gamma-S]) but not guanosine 5'[beta-thio]diphosphate (GDP[beta-S]) stimulate the activity over the range 1 microM to 100 microM. Other di- and tri-nucleotides also stimulate, but only at concentrations of 100 microM or higher. Added bivalent ions are not required either for NADH oxidation or guanine nucleotide stimulation. Bivalent ions (Mg2+ > Mn2+ > or = Ca2+) alone stimulate only slightly at low concentrations and then inhibit at high concentrations. The inhibitions are augmented by GDP or GTP [gamma-S] but not by GTP. Although the activity is the same, or less, in the presence of 0.5 mM MgCl2, GTP at 1-100 nM and other nucleotides at 0.1 mM or 1 mM still stimulate in its presence. The NADH oxidase is activated by mastoparan but aluminum fluoride is weakly inhibitory. Cholera and pertussis toxins elicit only marginal responses. Both the Mg2+ and the GDP and GTP[gamma-S] inhibitions (but not the GTP stimulations) shift to higher concentrations when the membrane preparations are first solubilized with Triton X-100. The results suggest a role for guanine nucleotides in the regulation of plasma membrane NADH oxidase, but with properties that differ from those of either trimeric or the low-molecular-mass G proteins thus far described.
Morré
D J
DJ
Department of Medicinal Chemistry, Purdue University, West Lafayette, IN 47907.
Davidson
M
M
Geilen
C
C
Lawrence
J
J
Flesher
G
G
Crowe
R
R
Crane
F L
FL
D000818:Animals; D002462:Cell Membrane / Q000201:enzymology; D002712:Chlorides; D004789:Enzyme Activation; D006056:Golgi Apparatus / Q000201:enzymology; D006150:Guanine Nucleotides / Q000494:pharmacology*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006153:Guanosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000494:pharmacology; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D015636:Magnesium Chloride / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology; D017895:Manganese Compounds; D009097:Multienzyme Complexes / Q000378:metabolism*; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D051381:Rats; D013873:Thionucleotides / Q000494:pharmacology
D002712:Chlorides; D006150:Guanine Nucleotides; D017895:Manganese Compounds; D009097:Multienzyme Complexes; D013873:Thionucleotides; D015636:Magnesium Chloride; D006153:Guanosine Diphosphate; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D008345:Manganese; C023427:guanosine 5'-O-(2-thiodiphosphate); D006160:Guanosine Triphosphate; C023107:NADH oxidase; D009247:NADH, NADPH Oxidoreductases; C025340:manganese chloride