Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01189 (beta-endorphin)
 21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Effects of ATP, acetyl phosphate (AcP) and p-nitrophenyl phosphate (p-NPP) on the inhibition of the Na+, K+-ATPase activity were studied. ATP, AcP and p-NPP were found to facilitate the ouabain-induced inhibition of the enzyme activity only after the injection of these phosphorylyzing agents into the erythrocyte ghosts. Inside the ghosts Na+ ions enhanced the effects of the phosphorylyzing agents. K+ ions in the environment removed the stimulating effects of ATP, AcP and p-NPP on the ouabain-induced inhibition of Na+, K+-ATPase activity. It is concluded that the sites of AcP and p-NPP hydrolysis as well as the active center for ATP are localized on the inner surface of the cell membrane.
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PMID:[Study of the interaction of Na+ and K+-ATPase of erythrocytes with ouabain. Effect of acetyl phosphate and p-nitrophenyl phosphate]. 13 45

The reaction of the oxygen isotope exchange (18O-exchange) was studied in the course of the Na, K-ATPase reaction. It was shown that the intermediary and direct 18O-exchanges occurred in the system in the presence of both ATP and p-NPP. These findings are indicative of the same intermediate during the hydrolytic process in both cases. The intermediary 18O-exchange was activated by N-ethylmaleimide, hydroxylamine and 2.0--1.5 18O atoms, respectively. The detection of 18O-exchange Ouabain had no effect on the exchange. The levels of intermediary 18O-exchange during ATP and p-NPP hydrolyses were equal to 1.3--1.4 and 2.0--1.5 18O atoms, respectively. The detection of 18O-exchange reactions at the intermediary steps of both ATP and p-NPP hydrolyses implies the identity of certain stages in the destruction of these substrates by Na, K-ATPase.
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PMID:[18 O-exchange during ATP and n-nitrophenylphosphate hydrolysis by Na, K-ATPase from bovine brain]. 14 48

The same isoenzyme of nonspecific alkaline phosphatase (APase), assayed with p-nitrophenylphosphate (p-NPP), was shown be present in different calcifying tissues, bone, calcifying cartilage, odontoblasts and enamel organ. Indications were also found that the enzymatic degradation of inorganic pyrophosphate (PPi) in calcifying tissues is mediated by APase. By using specific APase inhibitors, it was shown that two enzymes capable of degrading ATP exist. These were characterized in dentinogenically active odontoblasts, and it was concluded that one is the classical APase, the other is a Ca2+ and Mg2+ activated ATPase, named Ca2+-ATPase. The two phosphatases were solubilized from odontoblasts and separated. The localization of APase and Ca2+-ATPase in odontoblasts was investigated by subcellular fractionation and EM histochemistry. Routine methods for fixation were found to almost completely inactivate the enzymes. By using a mild fixation technique that preserved 80% of the enzyme activity, the main localization for both APase and Ca2+-ATPase was found to be in the membranes of intercellular vesicles located in the cell body and odontoblasts process. No activity was found in the cell membranes. It is concluded that there are at least two enzymes able to degrade phosphate compounds at alkaline pH in hard tissue forming cells. One is the nonspecific alkaline phosphatase (APase; EC 3. 1. 3. 1), which is active against p-NPP, PPi, glycerophosphates and ATP among other substrates. The other is a more specific Ca2+-ATPase (EC 3. 6. 1. 3). There seems to be an intimate relation between these two enzymes in the tissue. The function of APase in biological calcification is still obscure. In contrast, the finding of an ATP dependent, intravesicularly directed, transmembranous Ca2+-transport in vesicles derived from the microsomal fraction of odontoblasts may explain the role of Ca2+-ATPase.
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PMID:Odontoblast alkaline phosphatases and Ca2+ transport. 15 9

The substrate specificity and the effects of nucleotides and SH-blocking agents on the p-nitrophenylphosphatase activity of intact Ehrlich ascites tumor cells (EAT) cells were studied. DL-beta-Glycerophosphate, o-phosphoethanolamine, cholinephosphate, glucose-6-phosphate, o-carboxyphenylphosphate,, phosphoenolpyruvate and AMP were not attacked by intact cells. ATP is greater than GTP is greater than UPT is greater than PPi is greater than pNPP were cleaved with decreasing velocity. A stimulation of the cleavage of p-NPP by the following nucleotides was observed with decreasing effectivity: ATP is greater than ADP is greater than GTP is greater than UTP; AMP was ineffective. The phosphatase activity was not affected by malate, tartrate and glutathion disulfide. The SH blocking agents diamide and thimerosal were more effective inhibitors of the pNPPase than of the ATPase activity, whereas the hydrolysis of ATP is more affected by the ATP analog adenylylimidodiphosphate. The present data are best compatible with a double headed enzyme: Both active sites interact with ATP, only one is active against p-NPP and sensitive against SH-blocking agents.
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PMID:Further investigations on the p-nitrophenylphosphatase activity of intact Ehrlich ascites tumor cells. 20 18

The vector characteristics of the interacting Na+, K+-ATPase and ouabaine were studied in experiments on the restored ghosts of erythrocytes. It is shown that the effect of K+ on the enzyme activity is the same as in cases of using ATP and p-nitrophenylphosphate (p-NPP) as phosphorylating agents. ADP removes the p-NPP induced inhibition with ouabain. This effect is explained rather by addition of ADP to the enzyme substrate centre than by a decrease in the concentration of E1 approximately P phosphoform. Incorporation of labelled orthophosphate into p-nitrophenol (NP) in the presence of Na+, K+-ATPase preparations was not detected. It is shown that antibodies against the fraction of the brain microsomes inhibit K+-NPPases to a much less extent than Na+, K+-ATPase. The digitonin treatment does not remove (Na++ATP)-dependent increase in the K+-NPPase activity. A conclusion is drawn that the mechanisms of p-NPP hydrolysis differs from the mechanism of ATP hydrolysis.
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PMID:[Interaction of p-nitrophenylphosphate with Na+,K+-ATPase]. 22 60

Na+/K+-ATPase localization in the rectal wall of larval Aeshna cyanea (Insecta, Odonata) was studied with histochemical precipitation techniques and 3H-ouabain autoradiography in conjunction with biochemical measurements of enzyme activities and radiospectrometry of 3H-ouabain binding, respectively. The NPP-strontium and ATP-lead methods led to complete inhibition of Na+/K+-ATPase in this organ and hence to unreliable histochemical results. The 3H-ouabain binding technique revealed sodium pump sites at the basolateral plasma membranes of the absorptive rectal chloride epithelia.
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PMID:Comparative biochemical, histochemical and autoradiographic studies of Na+/k+-ATPase in the rectum of dragonfly larvae (Odonata, Aeshnidae). 23 44

The involvement of sodium and chloride ions in the process of alpha-melanocyte-stimulating hormone (a-MSH) release from hypothalamic neurons was investigated using perifused rat hypothalamic slices. Three different stimuli were found to increase a-MSH release from hypothalamic slices: high K+ concentration (50 mM), veratridine (50 microM), and the Na+/K(+)-ATPase inhibitor ouabain (1 mM). Spontaneous or K(+)-evoked a-MSH release was insensitive to the specific Na+ channel blocker tetrodotoxin (TTX; 1.5 microM) and to the blocker of K+ channels tetraethylammonium (TEA; 30 mM) or 4-aminopyridine (4-AP; 4 mM). In contrast, blockage of ouabain-sensitive Na+/K(+)-ATPase increased the resting level of a-MSH and caused a dramatic potentiation of K(+)-evoked a-MSH release. The Na+ channel activator veratridine (50 microM) triggered a-MSH release. This stimulatory effect was blocked by TTX and prolonged by TEA application, indicating the occurrence of voltage-sensitive Na+ and K+ channels on a-MSH neurons. Replacement of Na+ by impermeant choline ions from 95 to 60 mM did not alter K(+)-evoked a-MSH release. Conversely, dramatic reduction of the external Na+ concentration to 16 mM caused a robust increase of a-MSH secretion from hypothalamic neurons, likely through activation of the Na+/Ca2+ exchange system. These data indicate that the depolarizing effect of K+ results from direct activation of voltage-operated Ca2+ channels. The lack of effect of TEA on basal a-MSH release prompted us to investigate the possible involvement of chloride ions in the regulation of the spontaneous activity of a-MSH neurons. Substitution of Cl- for impermeant acetate ions did not affect basal or K(+)-evoked a-MSH release.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of ions and ionic channel activators or blockers on release of alpha-MSH from perifused rat hypothalamic slices. 169 47

The localization of an ouabain-sensitive potassium-dependent p-nitrophenylphosphatase part of the Na+,K(+)-ATPase complex in the white rat's brain has been studied at the ultrastructural level. The physiological pH of incubation medium highly increases the specificity of ultracytochemical enzyme demonstration. The main characteristics of the enzymatic p-NPP hydrolysis used for this methodological technique are discussed.
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PMID:[An electron microscopic study of the localization of the activity of the ouabain-sensitive, potassium-dependent p-nitrophenylphosphatase component of the Na, K-ATPase complex in the rat brain]. 196 42

The main characteristics of L-tyrosine (L-Tyr) uptake by B16/F10 malignant melanocytes are reported. This amino acid can be taken up by two systems, both of them being saturable. The first one would be system L. This system can be studied in cells preloaded with amino acids that are a good substrate for system L, such as L-methionine or L-tryptophan. The kinetic parameters for L-Tyr uptake by this transport system are Vm = 6.5 pmol L-Tyr/10(3) cells.min and Km around 130 microM. The second system, probably the system ASC, shows lower capacity but higher affinity than the former. This system can be detected only in cells previously depleted of amino acids, showing approximate kinetic values of Vm 0.05 pmol L-Tyr/10(3) cells.min and Km around 5 microM. It is shown that the increase in cell density yields a decrease in the rate of L-Tyr uptake by system L, but this increase does not affect the high affinity system, alpha-MSH does not affect significantly the L-Tyr uptake by both systems. 2-Amino bicyclo-(2,2,1)-heptane-2-carboxylic acid produces a remarkable inhibition of the rate of L-Tyr uptake, but alpha-methylaminoisobutyric acid does not affect the rate of transport of this amino acid. The absence of sodium produces a slight but reliable decrease in the rate of L-Tyr uptake, supporting the involvement of two different transport systems. The ionophores monensin and nigericin enhance the transport by system L, but this effect is suppressed by the presence of ouabain. This finding indicates that the (Na+ -K+)-ATPase is essential for the stimulating action of ionophores.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Transport of L-tyrosine by B16/F10 malignant melanocytes: characterization of the process. 198 30

The Na(+)-K(+)-adenosine triphosphatase (Na(+)-K(+)-ATPase) activity and beta-endorphin immunoreactivity were determined in rat brain at the acute stage of ischemia produced by unilateral occlusion of the middle cerebral artery (MCA). The effect of pretreatment with naloxone on these activities was also evaluated in the same model. After MCA occlusion, Na(+)-K(+)-ATPase activity was promptly reduced in the ischemic hemisphere and remained at a lower level than in the contralateral hemisphere during 90 minutes of ischemia. A single intraperitoneal 0.5-mg injection of naloxone prior to MCA occlusion attenuated the inactivation. On the other hand, beta-endorphin immunoreactivity was significantly increased following ischemia. The increase was marked in the ischemic hemisphere and was also observed in the contralateral hemisphere; this increase was not affected by the administration of naloxone. These results indicate the possibility that naloxone contributes to protecting the brain from ischemia through stabilizing the cellular membrane. The possible mechanism by which naloxone attenuates the inactivation of Na(+)-K(+)-ATPase in the ischemic brain is discussed in view of alterations of the central beta-endorphin system during ischemia.
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PMID:Alterations in Na(+)-K(+)-ATPase activity and beta-endorphin content in acute ischemic brain with and without naloxone treatment. 215 61


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