Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:O95477 (membrane-bound)
 29,236 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Oxytocin proteolysis was studied in vitro with purified synaptic membranes and in vivo after injection into the hippocampus of male Wistar Kyoto rats of different ages. When oxytocin was incubated in vitro with brain synaptic membranes obtained from 2-, 6-, and 12-month-old rats, no difference in the content of C-terminal and N-terminal fragments formed by membrane-bound aminopeptidase-like and endopeptidase-like enzymes, respectively, was found after high performance liquid chromatography separation and quantification by amino acid analysis. In contrast, the content of all fragments decreased by about 20%-25% when membranes obtained from 18- and 24-month-old rats were used. When [3H-Tyr2]oxytocin was injected in vivo in the hippocampus of 2-, 6-, 12-, and 18-month-old rats, no difference in the content of free [3H]-tyrosine and other [3H]-labelled fragments was found in the hippocampal peptidic extract after high performance liquid chromatography fractionation. However, the content of all radioactive fragments was about 50% lower in the extract from 24-month-old rats. The findings suggest that oxytocin proteolysis in brain decreases during aging. Such a decrease might counterbalance the impairment of central oxytocinergic transmission caused by the age-related decrease of oxytocin content in brain.
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PMID:Brain proteolysis of oxytocin in vitro and in vivo changes during aging in male rats. 783 89

The membrane-bound metalloprotease aminopeptidase N (APN, CD13, EC 3.4.11.2) is a well-established marker of normal and malignant cells of the myelomonocytic lineages. It is also expressed by leukemic blasts of a small group of patients suffering from acute or chronic lymphoid leukemia. CD13-specific monoclonal antibodies do not bind to the surface of normal B lymphocytes and APN-mRNA was not detectable by Northern analysis in normal lymphocytes or in T cell lines. A recent paper, however, describes the expression of CD13 on concanavalin A-stimulated T cells. Here, by means of enzymatic amplification of cDNA, cloning and sequencing of amplified cDNA fragments, in situ hybridization, and transcription start site mapping, evidence is provided that the human T cell lines HuT78 and H9 do contain APN-mRNA. Ala-pNA-hydrolyzing activity was detected in viable cells and cell homogenates as well as in size-fractionated protein fractions. Alanine-beta-naphthylamide (Ala-beta NA)-hydrolyzing activity was readily detectable after isoelectric focusing and blotting and was shown to be localized exclusively intracellularly in both cell lines. Usage of aminopeptidase-specific effectors revealed this activity to be distinct from CD13.
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PMID:Expression of the aminopeptidase N (CD13) gene in the human T cell lines HuT78 and H9. 790 39

Derivatives of 3-amino-2-tetralone were evaluated for their ability to selectively inhibit the membrane-bound zinc-dependent aminopeptidase (EC 3.4.11.2), isolated from porcine kidney. These novel nonpeptidic compounds are potent competitive inhibitors of the enzyme. Some of them have Ki values in the nanomolar range (g, Ki = 80 nM). Moreover, these inhibitors are selective for aminopeptidase-M (AP-M) since they do not inhibit aspartate aminopeptidase and arginine aminopeptidase and only poorly inhibit cytosolic leucine aminopeptidase at high concentrations (g, Ki = 70 microM). The availability of inhibitors which are selective for AP-M with respect to other mammalian aminopeptidases may aid in identifying new endogenous substrates and thus clarify the physiological or pathophysiological role(s) of AP-M.
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PMID:3-Amino-2-tetralone derivatives: novel potent and selective inhibitors of aminopeptidase-M (EC 3.4.11.2). 791 Apr 49

In order to identify the membrane-bound peptidase that is responsible for the degradation of endothelin (ET), an endothelin-1 (ET-1) degradation enzyme was solubilized from membrane fractions of porcine kidney with 1% Triton X-100, and subsequently purified by column chromatographies, i.e., diethylamino-Sepharose ion exchange, gel permeation, Con A Sepharose and hydroxyapatite chromatography. On DEAE-Toyopearl ion exchange column chromatography, the ET degradation enzyme and aminopeptidase were separated, but ET degradation enkephalinase activities were not separable. In order to separate ET degradation enzyme and enkephalinase, the active fractions were loaded on each of the column chromatographies: sephacryl S-200, Con A Sepharose or hydroxyapatite. The ET degradation activities were co-migrated with enkephalinase activities on all of the three chromatographies. In addition, the ET degradation activities were inhibited by thiorphan, phosphoramidon and EDTA, which are known to inhibit enkephalinase. These results suggest that ET degradation activity in the membrane fractions of the kidney is related to enkephalinase and may be involved in the degradation of ET-1 in vivo.
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PMID:Purification and characterization of endothelin-1 degradation activity from porcine kidney. 801 1

Membrane-bound pyroglutamyl-aminopeptidase activity cleaves the pyoglutamate amino acid bond of thyroliberin (TRH). Information concerning developmental variations in TRH has been reported. However, little is known about the ontogeny of the membrane-bound enzyme activities capable of hydrolyzing the mentioned tripeptide. In this work we have described decreases in membrane-bound pyroglutamyl-aminopeptidase (arylamidase) activity, from day 9 to day 20 after birth, in the hypothalamus, the striatum, the frontal, occipital and parieto-temporal cortices and the pituitary gland of the male and the female rat. The developmental profile is similar in rats of both sexes. We have not found significative changes between 20 and 25 postnatal days. The observed decreasing activity is developmentally coincident with the increases in thyroliberin and decreases in Hys-Pro diketopiperazine concentration in different brain areas. It is suggested that membrane-bound pyroglutamyl-peptidase activity could play a part in the normal development of thyroliberin physiology.
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PMID:Membrane-bound pyroglutamyl-arylamidase activity during the first postnatal month in several rat brain areas. 807 92

The effects of gentamicin treatment on functions of the plasma membrane-bound proteins in situ were investigated in primary culture of rabbit proximal tubular cells (PTC), a recognized model of renal epithelial cells. Activities of apical and basolateral enzymes, activities of phosphate, glucose and alanine sodium-coupled transport systems and leakage of the cytosolic enzyme lactate dehydrogenase (LDH) were determined in PTC grown in glucose-free culture medium as confluent monolayers and incubated with the aminoglycoside. Gentamicin altered in a concentration- and time-dependent manner the activity of dipeptidyl peptidase IV (DPP IV), neutral aminopeptidase (NAP), Na+K(+)-ATPase and the Vmax of sodium-dependent glucose and phosphate uptake, whereas gamma-glutamyl-transpeptidase (GGT) and sodium-dependent alanine uptake were unaffected. Identical concentration of gentamicin was required to induce LDH leakage and cell functions impairment. In contrast, under short time exposure, a condition where the enzyme activities were untouched, mercuric chloride inhibited to a similar extent the activity of the three sodium-coupled transport systems. These data suggest that whereas alterations in membrane fluidity might mediate the effects of gentamicin on membrane functions, the inhibition of transports by mercuric chloride rather reflects an effect on sodium permeability of the apical membrane. They also suggest that study of Na(+)-coupled transports in proximal tubular cells grown in primary culture is a simple and sensitive in vitro model to assess drug-induced nephrotoxicity.
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PMID:Primary culture of rabbit proximal tubules as a cellular model to study nephrotoxicity of xenobiotics. 810 56

Brain Tyr-aminopeptidase activity levels during two stages of the rat estrous cycle (estrous and proestrous), are described in this research. The study includes the activities of the soluble and the membrane-bound forms. Soluble Tyr-aminopeptidase activity shows a significant increase during the proestrous stage in the hypothalamus. The complete membrane-bound activity did not significantly change at any point. However, a significant rise was found in the membrane-bound puromycin insensitive aminopeptidase activity in the hypothalamus and the pituitary gland during the proestrous phase.
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PMID:Brain soluble and membrane-bound Tyr-aminopeptidase activities during the stages of estrous and proestrous in the female rat. 810 66

A ubenimex-sensitive aminopeptidase B-like enzyme was purified from the non-membrane-bound fraction of K562 cells by a series of chromatographic procedures and slab-gel electrophoresis. The apparent molecular mass of the enzyme was estimated to be 73 kDa by SDS-PAGE. The aminopeptidase activity was activated by chloride ions and inhibited by Zn2+, Cu2+, Cd2+, and p-chloromercuribenzoic acid. Ubenimex was a potent inhibitor of this aminopeptidase in the nanomolar range. The sequence of the N-terminus of the protein was not determined. Partial amino acid sequencing revealed that the N-terminus of this aminopeptidase B-like enzyme was blocked by acylation. The partial sequences of the two fragments produced by CNBr cleavage and an acylamino acid-releasing reaction showed this enzyme to be a new aminopeptidase.
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PMID:Purification and characterization of a ubenimex (Bestatin)-sensitive aminopeptidase B-like enzyme from K562 human chronic myeloid leukemia cells. 814 49

Met-enkephalin concentration-dependently and transiently inhibited the ileal twitch contraction and this inhibition gradually recovered with time. Bacitracin, phosphoramidon, thiorphan and captopril did not influence the twitch inhibition of met-enkephalin, but bestatin increased the twitch inhibitory potency of met-enkephalin and terminated it in a manner which almost paralleled that of untreated tissue. Transient inhibition of twitch contraction after tetanic stimulation (post-tetanic twitch inhibition) was obtained. Bestatin increased the potency of met-enkephalin and this was terminated within 2 min. Phosphoramidon tended to increase the potency and delayed the termination of post-tetanic twitch inhibition. Bacitracin, thiorphan and captopril did not influence either the potency or the termination of post-tetanic twitch inhibition. Morphine-induced twitch inhibition was not influenced by bacitracin, bestatin or phosphoramidon. These results suggest that bestatin-sensitive aminopeptidase and phosphoramidon-sensitive enkephalinase take part in post-tetanic twitch inhibition, acting in a different mode of action, and have an important role in the termination of the pharmacological action of endogenous opioids (post-tetanic twitch inhibition) in MPLM. This different mode of response of bestatin and phosphoramidon upon post-tetanic twitch inhibition may underlie that aminopeptidase is a more soluble enzyme and enkephalinase is membrane-bound in myenteric plexus-longitudinal muscle (MPLM).
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PMID:Effect of some peptidase inhibitors on exogenous and endogenous opioid actions in guinea-pig ileum. 814 19

Robenidine is an anticoccidial guanidine used as an additive in rabbit fodder. Because its action is restricted to the small intestine, the present work addresses the question whether robenidine affects the growth of the animals, sugar and amino acid intestinal transport and membrane-bound intestinal digestion. For this purpose we have determined the intestinal transport of the substrates, and the enzymatic activity of neutral aminopeptidase and sucrase. We have found that robenidine diminishes the tissue accumulation of L-leucine and D-galactose at long incubation times, and increases the transepithelial mucosal to serosal flux of both substrates. These results suggest that robenidine may stimulate the enterocyte basolateral membrane flux of sugars and neutral amino acids. These results have been corroborated by means of isolated brush border and basolateral membrane vesicles. Apart from these effects, robenidine has also been shown to increase the enzymatic activity of neutral aminopeptidase and sucrase and thus resulting in a better digestion of nutrients.
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PMID:Action of robenidine on the intestinal transport and digestion of nutrients in rabbit. 822 59


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