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)

Steroidogenesis by Y-1 adrenal tumor cells in culture is stimulated by ATP, adenyl-5'-yl imidodiphosphate (App(NH)), adenosine 5'(beta, alpha-methylene)triphosphate (App(CH2)p), ADP, AMP, NAD, FAD, and adenosine but not by adenine or other nucleoside triphosphates. ATP, App(NH)p, App(CH2)p, and adenosine are active in the micromolar range. Like adrenocorticotropic hormone (ACTH), the onset of stimulation is immediate and occurs to the same extent. Also active are 2'- and 5'-deoxyadenosine and 2-chloroadenosine whereas adenine xyloside, L-riboside, or arabinoside have very low activity. Stimulation is accompanied by rounding of the cells. Dipyridamole, an inhibitor of adenosine transport, increased the response to low concentrations of adenosine, suggesting that adenosine acts externally. Stimulation of steroidogenesis by adenosine or phosphorylated adenosine compounds fails to occur in the presence of crystalline adenosine deaminase, and the effect of the enzyme on adenosine, ATP, or NAD stimulation is reversed by the competitive inhibitor erythro-9-[3-(nonane-2-ol)]adenine. This suggests that the enzyme acts specifically on adenosine and a requirement for the conversion of the above compounds to adenosine seems probable. The inhibition of cAMP effects by adenosine deaminase suggests that some of its effects are also mediated by conversion to adenosine. Similar stimulation is seen in I-10 Leydig tumor cells, but an ACTH-resistant mutant of Y-1 cells, called OS-3, is relatively resistant to adenosine. Adenosine and 2-chloroadenosine stimulate adenylate cyclase in membranes from Y-1 and I-10 cells at concentrations slightly greater than are effective for steroidogenesis. Other nucleosides are ineffective. Like the NH2-terminal 24 residues of adrenocorticotropic hormone (1-24 ACTH), the adenosine effect in Y-1 membranes is rapid and is on the Vmax intercept (versus ATP) and not on the Km. In contrast to steroidogenesis, adenosine is only a partial agonist for adenylate cyclase. It effect occurs in the presence of ITP, GTP, or guanyl-5'-yl imidodiphosphate (Gpp(NH)p). Theophylline inhibits adenosine-stimulated steroidogenesis. Inhibition of adenylate cyclase occurs in the same concentration range but is of the mixed type.
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PMID:Activation of steroidogenesis and adenylate cyclase by adenosine in adrenal and Leydig tumor cells. 18 24

The ability of cytochalasin B to inhibit the steroidogenic response of mouse adrenal tumor cells (Y-1) to adrenocorticotropin (ACTH) was examined with two aims: to consider the specificity of the inhibitor and to determine at what point(s) in the steroidogenic pathway it acts. Cytochalasin B did not inhibit protein synthesis or transport of [3H]-cholesterol into the cells nor did it alter total cell concentration of ATP. Together with previous evidence, this suggests that the effects of cytochalasin observed are relatively specific in these cells. Cytochalasin inhibits the increase in conversion of [3H]cholesterol to 20alpha-[3H]dihydroprogesterone (20alpha-hydroxypregn-4-en-3-one: a major product of the steroid pathway in Y-1 cells) produced by ACTH but does not inhibit conversion of cholesterol to pregnenolone by mitochondrial and purified enzyme preparations from Y-1 cells and bovine adrenal, respectively. Cytochalasin does not inhibit the conversion of pregnenolone to 20alpha-dihydroprogesterone but was shown to inhibit increased transport of [3H]cholesterol to mitochondria resulting from the action of ACTH. These findings indicate that cytochalasin acts after cholesterol has entered the cells and before it is subjected to side-chain cleavage in mitochondria. In view of the known action of cytochalasin on microfilaments, it is proposed that these organelles are necessary for the transport of cholesterol to the mitochondrial cleavage enzyme and that at least one effect of ACTH (and cyclic AMP) is exerted upon this transport process. The specificity of the effects of cytochalasin is considered in relation to this conclusion.
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PMID:Response of adrenal tumor cells to adrenocorticotropin: site of inhibition by cytochalasin B. 19 28

An assessment was made of some of the basic parameters responsible for the modulation of adenylate cyclase activity in a bovine adrenocortical plasma-membrane preparation. When determined at 0.1 mM-ATP, basal adenylate cyclase activity increased with increasing MgCl2 concentrations, whereas in the presence of corticotropin activity was essentially maximal at 10mM-MgCl2; high concentrations (25mM) of MgCl2 inhibited adenylate cyclase activity determined in the presence of both corticotropin and GTP. At all MgCl2 concentrations, corticotropin and GTP activated the enzyme in a synergistic fashion. The magnitude of the stimulation of basal activity produced by corticotropin was a function of Mg2+ concentration, whereas that produced by GTP appeared largely independent of Mg2+ concentration. Adenylate cyclase activity in the bovine adrenal membrane was half-maximally stimulated by corticotropin concentrations in the range 0.3--1.0 nM. The concentration of corticotropin evoking half-maximum response was not significantly affected by raising the free Mg2+ concentration from 0.4 to 4.9 mM, nor by the presence of GTP. In the presence of GTP, high concentrations (over 1 micrometer) of corticotropin inhibited adenylate cyclase activity, although no inhibition was apparent in the absence of guanine nucleotide.
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PMID:Modulation of the response of bovine adrenocortical adenylate cyclase to corticotropin. 20 64

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

Lutropin and human choriogonadotropin stimulated the endogenous chromatin-associated polymerase activity in purified chromatin prepared from nuclei of bovine corpus luteum. Chromatin was incubated in two different buffer systems: one that mainly supports the activity of polymerase I, another that supports the activity of polymerase II and is largely alpha-amanitin sensitive. The hormones lutropin and chorigonadotropin stimulated an increase in the rate of incorporation of [14C]ATP or [14C]UTP into RNA in both buffer systems. Follitropin, prolactin and beta-corticotropin had no stimulatory effect. Neither the alpha nor beta subunit of lutropin stimulated RNA synthesis. When premixed, the subunits rapidly formed the active molecule. A maximum response to RNA synthesis was achieved by a 10(-9) M concentration of human choriogonadotropin. Considerable activity was obtained at 10(-11) M human choriogonadotropin. There was no lutropin stimulation to RNA synthesis using calf thymus DNA and Escherichia coli RNA polymerase.
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PMID:Lutropin stimulation of RNA synthesis in corpus luteum chromatin. 32 86

A chronobiological study was carried out in 6 male patients (67-71 years), suffering from Alzheimer-type dementia (ATD) and 6 male patients (52-74 years) suffering from multi-infarct dementia (MID), to evaluate their 24-hour beta-endorphin and cortisol secretory patterns. Six healthy male adults (28-37 years) and 6 healthy elderly male subjects (78-84 years) constituted the control groups. Blood samples were drawn every 4 h from 8.00 to 20.00 h and every 2 h from 24.00 to 6.00 h. Mean 24-hour beta-endorphin levels were significantly (p < 0.05) higher in the ATD patients (39.2 +/- 1.5 ng/l) than in the other groups (33.8 +/- 1.1, 30.1 +/- 1.6 and 33.2 +/- 1.1 ng/l in the elderly subjects, the adults and the MID patients, respectively). The circadian rhythm was absent in the ATP patients, in the elderly subjects and the MID patients. No differences in plasma cortisol circadian rhythm were observed among the four groups. Our data indicate that changes in circulating beta-endorphin concentrations and circadian pattern may be due to the aging process.
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PMID:Twenty-four-hour beta-endorphin secretory pattern in Alzheimer's disease. 145 59

In homogenate of rat olfactory bulb, the opioid receptor agonists beta-endorphin, Leu-enkephalin, and dynorphin A stimulated adenylate cyclase activity in a concentration-dependent manner, with half-maximal effects displayed at 22, 63, and 176 nM, respectively. The maximal stimulation of the enzyme activity corresponded to about a 40% increase of basal activity for all three peptides. Naloxone antagonized the stimulation of beta-endorphin, Leu-enkephalin, and dynorphin A, with pA2 values of 8.0, 7.7, and 8.1, respectively. Kinetic analysis performed with Leu-enkephalin showed that the opioid peptide increased the Vmax of the enzyme, without changing the Km for the substrate Mg-ATP. Moreover, the opioid stimulation was associated with a significant increase of the affinity of the enzyme for Mg2+ activation and occurred in membranes incubated in a Ca2(+)-free medium. Addition of exogenous GTP at micromolar concentrations was absolutely necessary for the detection of the opioid effect. Treatment of olfactory bulbs with cholera toxin did not alter the stimulation of adenylate cyclase by Leu-enkephalin. However, the opioid stimulation disappeared in membranes obtained from bulbs injected with pertussis toxin. These results demonstrate the presence in the brain of a new functional class of opiate receptors coupled to stimulation of adenylate cyclase via a transduction mechanism that is Ca2+ independent and seems to involve a pertussis toxin-sensitive GTP-binding protein.
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PMID:Naturally occurring opioid receptor agonists stimulate adenylate cyclase activity in rat olfactory bulb. 167 23

1. A sucrose-gap technique was used to investigate the neuromodulatory actions of enkephalins on non-adrenergic, non-cholinergic inhibitory junction potentials (IJPs) in the circular muscle of the human large intestine. 2. The native enkephalins, [Leu5]enkephalin (LENK) and [Met5]enkephalin (MENK) caused a concentration-dependent reduction in amplitude of IJPs without a significant effect on the smooth muscle membrane. 3. The actions of LENK and MENK were mimicked by the delta-selective opioid receptor agonists [D-Pen2, D-Pen5]enkephalin (DPDPE) and [D-Ala2, D-Leu5]enkephalin (DADLE). 4. The actions of LENK, MENK and DPDPE were antagonized to similar extents by the delta-selective opioid receptor antagonist ICI 174,864. 5. The mu-selective opioid receptor agonist [D-Ala2, Me Phe, Gly-ol5]enkephalin was approximately 100-fold less potent than any of the native or synthetic enkephalins at reducing the amplitude of the IJP. Dynorphin A and beta-endorphin both had very weak activity. 6. Responses to all of the agonists were inhibited by naloxone. The degree of antagonism of DPDPE or DADLE by naloxone (1 microM) was the same as that of LENK or MENK. 7. Neither MENK nor LENK affected hyperpolarization of the smooth muscle membrane induced by ATP or 5-hydroxytryptamine. Vasoactive intestinal polypeptide (1 pM-1 microM) did not produce any observable responses and this lack of reactivity was not affected by the enkephalins. 8. It is concluded that in the circular muscle of the human colon, LENK and MENK can act on prejunctional delta-opioid receptors to produce inhibition of non-adrenergic, non-cholinergic inhibitory neuromuscular transmission. Possible physiological significance of this prejunctional receptor is discussed.
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PMID:Enkephalins modulate inhibitory neuromuscular transmission in circular muscle of human colon via delta-opioid receptors. 196 52


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