Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.3.14 (ATP synthase)
 7,042 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Yeast mitochondrial ATP synthase has three regulatory proteins, ATPase inhibitor, 9K protein, and 15K protein. The 9K protein binds directly to purified F1-ATPase, as does the ATPase inhibitor, but the 15K protein does not [Hashimoto, T. et al. (1987) J. Biochem. 102, 685-692]. In the present study, we found that 15K protein bound to purified F1F0-ATPase, forming an equimolar complex with the enzyme. The apparent dissociation constant was calculated to be 1.4 x 10(-5) M. The ATPase inhibitor and 9K protein also bound to F1F0-ATPase in the presence of ATP and Mg2+, and the dissociation constants of their bindings were about 3 X 10(-6) M. They bound to the enzyme competitively in the absence of 15K protein, but in its presence, they bound in equimolar amounts to the enzyme. The ATP-hydrolyzing activity of the enzyme-ligand complex was greatly influenced by the order of bindings of ATPase inhibitor and 9K protein: when the ATPase inhibitor was bound first, the activity of the enzyme was inhibited completely and was not restored by 9K protein, but when 9K protein was added first, the activity was inhibited only partially even after equimolar binding of the ATPase inhibitor to the enzyme. These observations strongly suggest that the 15K protein binds to the F0 part and functions to hold the ATPase inhibitor or 9K protein on the F1 subunit.
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PMID:Simultaneous bindings of ATPase inhibitor and 9K protein to F1F0-ATPase in the presence of 15K protein in yeast mitochondria. 217 20

Two proteinaceous factors, 15K and 9K proteins, which acted together to stabilize the inactivated yeast F1F0-ATPase-inhibitor complex [Hashimoto, T., et al. (1984) J. Biochem. 95, 131-136] were hardly distinguishable from the sigma and epsilon subunits, respectively, of yeast F1-ATPase by sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis. However, they were clearly distinguishable from these subunits by analyses of the sequences at their amino terminals and by immunoblotting combined with SDS polyacrylamide gel electrophoresis. The two stabilizing factors and an ATPase inhibitor existed in mitochondria in equimolar ratios to F1-ATPase. These three protein factors were not present in purified F1-ATPase or in F1F0-ATPase preparations, but remained in the mitochondrial membranes after extraction of F1F0-ATPase with Triton X-100. These observations strongly suggest that the two stabilizing factors and the ATPase inhibitor form a regulatory substructure of mitochondrial ATP synthase, in addition to the F1 and F0 subunits.
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PMID:Existence of stoichiometric amounts of an intrinsic ATPase inhibitor and two stabilizing factors with mitochondrial ATP synthase in yeast. 287 60

A previously found yeast-mitochondrial protein fraction stabilizing the inactivated complex between mitochondrial ATPase and intrinsic ATPase inhibitor (Hashimoto, T., et al. (1983) J. Biochem. 94, 715-720) was separated into two proteins by high performance liquid chromatography on a cation exchanger. The molecular weights of the factors were estimated to be 9,000 and 15,000 daltons by sodium dodecyl sulfate (SDS)-gel electrophoresis. Both factors were required to stabilize a complex of inhibitor and proton-translocating ATPase (F1F0-ATPase) either in its purified form or in mitochondrial membranes. On the other hand both factors together could not stabilize a complex of the inhibitor and F1-ATPase, suggesting that both factors act together with the F0-portion. The factors also facilitated very efficiently the binding of ATPase inhibitor to F1F0-ATPase in the presence of ATP and Mg2+. Both the 15,000 and 9,000 dalton stabilizing factors were hardly distinguishable from delta- and epsilon-subunit, respectively, on an SDS-gel electrophoregram, but immuno-diffusion assay showed that neither factor was present in the purified F1-ATPase containing the delta- and epsilon-subunit.
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PMID:Purification and properties of factors in yeast mitochondria stabilizing the F1F0-ATPase-inhibitor complex. 620 Apr 68