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)

Among several bioactive substances known as coupling factors, transforming growth factor-beta (TGF-beta), interleukin-1 (IL-1), and prostaglandin (PG) E1 and E2 increased not only the activity of alkaline phosphatase but also the rate of incorporation of 45Ca2+ into ROS 17/2.8 during a 3-day culture: the former two factors are known to be formed at the site where bone is resorbed, while PG's are known as one of the factors involved in bone resorption. Parathyroid hormone, another hormone that affects bone metabolism, elevated the incorporation of 45Ca2+ by and decreased the alkaline phosphatase activity of the cells. The facts indicate the possibility that the osteoblastic cells are involved in the transport of calcium ions when bones are being resorbed. On the other hand, when these osteosarcoma cells were cultured in DMEM containing ascorbate and beta-glycerophosphate, followed by staining with silver nitrate by the procedure of von Kossa, there appeared many groups of cells that were positively stained as dark brown spots. Cells were then cultured under the same conditions in the presence of radioactive calcium, and the radioactivity accumulated was measured. The result showed that the presence of both ascorbate and beta-glycerophosphate in the culture medium dramatically increased the accumulation of 45Ca2+. It appears from these facts that ROS 17/2.8 cells are capable of incorporating and/or accumulating calcium ion if they are cultured under appropriate conditions. These cells will probably be able to produce a calcified matrix in vitro.
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PMID:[Effects of L-ascorbic acid and bone metabolism factors on alkaline phosphatase activity of and 45Ca2+ incorporation by ROS 17/2.8 cells]. 213 81

Parathyroid hormone (PTH) has been shown to bind specifically to the beta subunit of the mitochondrial ATPase on nitrocellulose blots. We have now examined this interaction further, using intact mitochondria, submitochondrial particles, and the purified F1 ATPase. With intact mitochondria, 1 microM concentrations of PTH and its biologically active 1-34 fragment activate the ATPase about 3-fold. This effect was reduced to a 1.4-fold activation with 3-34 and 7-34 fragments of the hormone, and oxidized PTH gave no detectable activity. Activation could only be observed below pH 7. PTH had no significant effect on the activity of the purified enzyme or on submitochondrial particles. However, specific binding of an iodinated PTH analog, [Nle 8,18-Tyr 34] bPTH (1-34) amide, was found with submitochondrial particles and the purified ATPase. Binding affinity with the purified enzyme was about 10(-3) that of the plasma membrane receptor, and the molar stoichiometry was close to 1:1 (PTH:intact enzyme). With submitochondrial particles the affinity was about 10-fold higher than with the purified enzyme. This binding was further examined with PTH derivatives and fragments, and compared to that seen in the plasma membrane receptor. Oxidation of methionine 18 in PTH reduced the affinity about 50%, oxidation of methionine 8 reduced the affinity 95%, and oxidation of both methionines further decreased affinity in both membranes and submitochondrial particles. However, when compared to the native hormone, the 3-34 and 7-34 PTH fragments had much higher affinity for the submitochondrial particles than for the plasma membranes. PTH also reduced chemical crosslinking of the ATP analog, p-fluorosulfonyl benzoyl 5'-adenosine, to the alpha subunit of this enzyme, but did not alter labeling of the enzyme with 3'-O-(4'-benzoyl) benzoyl ATP, suggesting that the hormone binds near a regulatory nucleotide binding site. Direct chemical crosslinking of PTH to the beta-subunit of the enzyme was attained with a cleavable, photoactivate crosslinker, sulfosuccinimidyl 2-(p-azidosalicylamido) ethyl-1,3-dithiopropionate. The crosslinked protein was cleaved with cyanogen bromide and the labeled fragments were sequenced. The labeled fragments were found to be segments of the protein which have previously been implicated as being close to the noncatalytic ATP binding sites.
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PMID:Characterization of the interaction of parathyroid hormone with the mitochondrial ATPase. 214 4