Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P20020 (adenosine triphosphatase)
 3,299 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In order to elucidate the biochemical basis for the selective cytotoxicity of D-glucosamine to neoplastic cells, the effect of glucosamine on the growth and several functions of mastocytoma P-815 cells were examined. Incubation of mastocytoma cells with 5 mM glucosamine resulted in a marked inhibition of growth and a significant reduction of cellular uptake and oxidation of glucose and of cellular levels of adenosine triphosphatase (ATP). Glucosamine also reduced the uridine nucleotide pool sizes, and accumulated uridine diphosphate (UDP)-N-acetylglucosamine. However, growth inhibition by glucosamine, which was reversed by glucose, was not prevented by exogenous uridine. In addition, glucosamine suppressed the phosphorylation of thymidine and its incorporation into deoxyribonucleic acid (DNA). The suppression of cell division by glucosamine was accompanied by the elevation of several functions of mastocytoma cells, including the accumulation of adenosine-3', 5'-monophosphate (cAMP), histamine, and serotonin. The incorporation of [(35)S]SO(4)(2-) into acidic glycosaminoglycan was also increased. Of these functional alterations, the elevation of cAMP levels was the earliest detectable change, indicating that growth and functions of mastocytoma cells are also regulated by cAMP. However, glucosamine did not affect the adenylate cyclase activity of plasma membrane in vitro, suggesting the necessity of intact membrane structure for the action of glucosamine.
 ...
PMID:Effect of D-glucosamine on growth and several functions of cultured mastocytoma P-815 cells. 626 62

1 The effect of (+/-)-, (+)- and (-)-verapamil on the Ca2+-binding, Ca2+-transporting activity, and Ca2+-dependent adenosine triphosphatase (ATPase) activity of isolated cardiac sarcolemmal preparations was studied. Enzymatic treatment was used to establish the nature of the sites facilitating [14C]-(+/-)-verapamil binding. 2 (+/-)-Verapamil 1 microM inhibited the passive binding of 45Ca2+. The (+/-)- and (-)-isomers were equiactive. 3 (+/-)-Verapamil 1 microM inhibited the ATP-dependent transport of 45Ca2+ and the associated activation of the Ca2+-sensitive ATPase. The activity resided in the (-)-isomer. 4 Lineweaver-Burk plots for the initial rates of ATP-dependent transport showed that the inhibition induced by the (-)-isomer was accompanied by a reduced Km and Vmax. 5 Enzymatic removal of N-acetyl neuraminic acid and galactose residues increased [14C]-(+/-)-verapamil binding; removal of N-acetylglucosamine and treatment with phospholipase C and trypsin decreased the binding. 6 These results have been interpreted to mean that (-)-verapamil interferes with the ATP-dependent Ca2+-transporting properties of the sarcolemma, and that this effect is accompanied by an altered activity of the intrinsic Ca2+-sensitive ATPase. N-acetylneuramic acid and galactose residues do not provide binding sites for verapamil at the cell surface.
 ...
PMID:The effect of verapamil on the Ca2+-transporting and Ca2+-ATPase activity of isolated cardiac sarcolemmal preparations. 645 Dec 52