Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Luminal proteins of the endoplasmic reticulum (ER) share a common carboxy-terminal tetrapeptide which is necessary and sufficient for their retention in the ER. In animal cells this retention signal is usually KDEL, whereas the yeast Kluyveromyces lactis uses the closely related sequences HDEL and DDEL. The yeast ERD2 gene has been shown to determine the capacity and specificity of the retention system, implying that it encodes a sorting receptor. This receptor is thought to retrieve escaped ER proteins from the Golgi, where a human homologue of this protein has been located. This dual function of binding and retrieval requires a receptor with highly specific binding at a specific location in the cell (Golgi but not ER). Here, a region of the ERD2 protein responsible for the specificity of ligand recognition has been identified using three independent approaches. A single amino acid residue is shown to selectively affect HDEL retention: substitution of residue 51 of the K. lactis receptor is sufficient to abolish recognition of HDEL but not DDEL, generating a novel retention phenotype.
J Mol Biol 1992 Mar 05
PMID:Changing the specificity of the sorting receptor for luminal endoplasmic reticulum proteins. 131 4

Clusterin is a heterodimeric glycoprotein synthesized and secreted by rat Sertoli cells and epididymal epithelium. The goal of this study was to determine the presence of clusterin in the luminal fluid of the cauda epididymides and its association with the membranes of developing spermatozoa in the presence and absence of androgen. We have previously demonstrated by two-dimensional (2-D) Western blot probing for clusterin that in epididymal fluid the amounts of clusterin were: caput greater than corpus greater than cauda. Luminal fluid from cauda epididymides was collected from control and orchiectomized rats (6 and 12 days) and orchiectomized animals that received testosterone implants. Equal volumes of fluid were analyzed by 2-D Western blot probing for clusterin. Following orchiectomy, there was an increase in clusterin in the luminal fluid after 6 days and maximal amount after 12 days compared with control cauda fluid. Orchiectomized animals which received testosterone treatment showed levels of clusterin comparable to that of controls. Serum clusterin was detected in fluid of orchiectomized animals with and without testosterone. Western blots of cauda sperm membrane extracts of control animals and orchiectomized animals treated with testosterone had a very low level of epididymal clusterin, whereas extracts collected from orchiectomized animals revealed high levels of clusterin. We suggest that, in the normal animal, clusterin is secreted into the lumen of the proximal epididymis where it binds to the sperm membrane. In the distal epididymis, clusterin dissociates from sperm and is processed (proteolysis/endocytosis). We hypothesize that, in the absence of androgen, the processing and regulation of clusterin is disrupted.
Mol Reprod Dev 1992 May
PMID:Clusterin (SGP-2) in epididymal luminal fluid and its association with epididymal spermatozoa in androgen-deprived rats. 151 50

The major regulators of endometrial function are oestrogen and progesterone, which act through binding their nuclear receptors and by activating transcription of their target genes. Interactions between steroid receptors and transcription proteins, e.g. c-JUN/AP-1, can modulate steroid action at the transcriptional level. The 19-nortestosterone-derived progestin, levonorgestrel, is used for contraception, treatment of menorrhagia and for endometrial protection during hormone replacement therapy, but the signalling pathways of its action are totally undefined. We examined the effect of an intrauterine system, releasing 20 microg of levonorgestrel per 24 h (LNG-IUS), on immunoreactive oestrogen receptor, progesterone receptor, c-JUN and Ki-67 expression in 29 endometrial specimens, obtained from fertile women using the LNG-IUS for contraception. Moderate to strong immunostaining for oestrogen receptors was observed in the stromal cells in all specimens, in glandular epithelial cells in 26 cases and in flattened luminal epithelial cells in 17 specimens. Decidualized stromal cells showed no progesterone receptor immunoreactivity in 19 of the 29 specimens, and weak to moderate immunostaining in 10 cases. Luminal epithelial cells were negative for progesterone receptor in all samples. Intense nuclear staining for C-JUN was observed in epithelial cells in 26 and in decidualized stromal cells in all 29 of the samples. In 16 samples, Ki-67 immunoreactivity was evaluated as weak to moderate in decidualized stroma, and in 13 samples absent. Our data demonstrate that intrauterine release of LNG maintains constant expression of C-JUN and exerts progestational effects in the endometrium in the absence of progesterone receptors. In contrast, LNG-IUS inhibits several cellular responses to oestrogen despite the presence of endogenous oestrogen and oestrogen receptors. These data suggest that the progestational effects induced by progesterone and levonorgestrel are mediated through different signalling pathways.
Mol Hum Reprod 1998 Dec
PMID:The effect of intrauterine levonorgestrel use on the expression of c-JUN, oestrogen receptors, progesterone receptors and Ki-67 in human endometrium. 987 60

A net secretion of chloride stimulated by carbamylcholine was observed in whole trachea. Luminal anthracene-9-carboxylic acid inhibited the net secretion of chloride and the transepithelial potential difference across the isolated trachea. Submucosal ouabain inhibited the net secretion of chloride and submucosal ouabain, or submucosal bumetanide inhibited the transepithelial potential difference across the isolated trachea. Short-circuited flat sheets of trachea manifested a net secretion of chloride induced by carbamylcholine. Serosal ouabain inhibited the short-circuit current and net chloride flux across isolated flat sheets of trachea.
Comp Biochem Physiol A Mol Integr Physiol 1999 Jan
PMID:Chloride transport in the ferret trachea. 1021 34

Luminal testicular factors are known to be important for the regulation of the epididymal epithelium. The present study was undertaken to test the hypothesis that complete deprivation of luminal factors by efferent duct ligation (EDL) would induce apoptosis in the epididymal epithelium, as does removal of trophic factors from other cell types. Additionally, experiments were performed to determine whether the apoptosis detected was p53 dependent or independent. Apoptosis detection was by terminal deoxynucleotidyl-mediated deoxyuridine triphosphate-biotin nick-end labeling and by DNA fragmentation studies. EDL caused loss of testicular luminal contribution in zone 1A of the rat epididymis (proximal initial segment) within 6 hr and induced epithelial apoptosis within 12 hr of the efferent duct obstruction. The wave of apoptosis in zone 1A was completed by three days after EDL and was followed by a much smaller wave in zone 1B which peaked three days after EDL. Significant apoptosis was not detected in any epididymal region distal to the initial segment for periods as long as 15 days after EDL. p53, a key apoptotic-pathway molecule in many tissues and conditions was tested by immunohistochemical and Western blot techniques and was not upregulated in the initial segment epithelium within the time cells were undergoing apoptosis and well before the wave of apoptosis was complete. It was concluded that epithelial apoptosis in the initial segment of the rat epididymis is induced by deprivation of luminal testicular factors, is localized to the proximal and middle initial segment, and is p53 independent.
Mol Reprod Dev 1999 Jun
PMID:p53 independent, region-specific epithelial apoptosis is induced in the rat epididymis by deprivation of luminal factors. 1033 57

We previously reported that in the rabbit, the vitamin D-dependent calcium binding protein 28K (CaBP 28K) increases calcium (Ca2+) transport in the distal tubule by opening a high affinity Ca2+ channel in the luminal membrane. Since Na+ and Ca2+ transports are interdependent in this membrane, we questioned whether the calbindin has any influence on Na+ transport. Luminal membranes from rabbit proximal and distal tubules were purified and 22Na uptake by the membrane vesicles was measured using the rapid filtration technique. The vesicles were loaded with 280 mM mannitol and 20 mM Tris-Hepes pH 7.4, with either 3 microM CaBP or the carrier. Incubation medium contained 1 mM 22NaCl, 278 mM mannitol, and 20 mM Tris-Hepes pH 7.4. The presence of 3 microM CaBP 28K in the distal luminal membrane vesicles increased the 0.5 mM Ca2+ uptake from 0.91 +/- 0.21 to 1.84 +/- 0.33 pmol/microg/10 s (P < 0.01) and decreased 1 mM Na+ uptake from 0.62 +/- 0.15 to 0.27 +/- 0.08 pmol/microg/10 s (P < 0.05). A similar decrease of Na+ uptake was observed in proximal luminal membrane experiments. The effect on Na+ uptake by the distal membrane was dose-dependent with a IC50 of 4.5 microM. Addition of 2 mM Ca2+ to the incubation medium decreased 1 mM Na + uptake from 0.62 +/- 0.15 to 0.49 +/- 0.12 pmol/microg/10 s (P < 0.05), but did not influence the effect of CaBP 28K on Na+ uptake. Experiments performed in the presence and absence of ethyl isopropyl amiloride (EIPA) suggest that the effect of calbindin involves the Na+/H+ exchanger activity.
Mol Cell Endocrinol 1999 Jun 25
PMID:Effect of calbindin D 28K on sodium transport by the luminal membrane of the rabbit nephron. 1043 33

Luminal levels of nitric oxide/nitrite are high in colitis. Whether nitric oxide is injurious or protective to human colonocytes is unknown and the role of nitric oxide in the genesis of colitis unclear. The aims were to establish whether nitric oxide was injurious to oxidation of substrates (n-butyrate and D-glucose) in isolated human and rat colonocytes both alone and in the presence of hydrogen sulfide and hydrogen peroxide, agents implicated in cell damage of colitis. Nitric oxide generation from S-nitrosoglutathione was measured by nitrite appearance. Colonocytes were isolated and incubated with [1-14C] butyrate or [6-14C] glucose and 2.6 microM nitric oxide, 1.5 mM sodium hydrogen sulfide or 2.5 mM hydrogen peroxide. Acyl-CoA esters were measured by high performance liquid chromatography, 14CO2 radiochemically and lactate/ketones by enzymic methods. Results indicate that nitric oxide very significantly (p < .001) reduced acyl-CoA formation but did not impair 14CO2 generation. Peroxide and sulfide with nitric oxide resulted in significant reduction (p < 0.01) of substrate oxidation to CO2. Sulfide significantly stimulated release of nitric oxide from S-nitrosoglutathione. The principal conclusion is that nitric oxide diminishes CoA metabolism in colonocytes. CoA depletion has been observed in chronic human colitis for which a biochemical explanation has been lacking. For acute injurious action in human colonocytes nitric oxide requires co-action of peroxide and sulfide to impair oxidation of substrates in cells. From current observations treatment of colitis should aim to reduce simultaneously nitric oxide, peroxide and sulfide generation in the colon.
Mol Cell Biochem 2000 Mar
PMID:Nitric oxide effect on colonocyte metabolism: co-action of sulfides and peroxide. 1083 6

To identify specific transporters that drive xenobiotics from central nervous system to blood, the accumulation of fluorescent drugs was studied in isolated capillaries from rat and pig brain using confocal microscopy and quantitative image analysis. Luminal accumulation of daunomycin and of fluorescent derivatives of cyclosporine A (CSA) and ivermectin was concentrative, specific, and energy-dependent (inhibition by NaCN). Transport was reduced by PSC 833, ivermectin, verapamil, CSA, and vanadate, but not by leukotriene C(4) (LTC(4)), indicating the involvement of P-glycoprotein. Luminal accumulation of the fluorescent organic anions sulforhodamine 101 and fluorescein methotrexate was also concentrative, specific, and energy-dependent. LTC(4), chlorodinitrobenzene, and vanadate reduced transport of these compounds, but PSC 833 and verapamil did not, indicating the involvement of a multidrug resistance-associated protein (Mrp). Immunostaining localized P-glycoprotein and Mrp2 to the luminal surface of the capillary endothelium and quantitative polymerase chain reaction showed Mrp1 and Mrp2 expression. Finally, the HIV protease inhibitors saquinavir and ritonavir were potent inhibitors of transport mediated by both P-glycoprotein and Mrp. These results validate a new method for studying drug transport in isolated brain capillaries and implicate both P-glycoprotein and one or more members of the Mrp family in drug transport from central nervous system to blood.
Mol Pharmacol 2000 Dec
PMID:Xenobiotic transport across isolated brain microvessels studied by confocal microscopy. 1109 74

Because of its possible importance in cystic fibrosis (CF) pulmonary pathogenesis, the effect of anion and liquid secretion inhibitors on airway mucociliary transport was examined. When excised porcine tracheas were treated with ACh to induce gland liquid secretion, the rate of mucociliary transport was increased nearly threefold from 2.5 +/- 0.5 to 6.8 +/- 0.8 mm/min. Pretreatment with both bumetanide and dimethylamiloride (DMA), to respectively inhibit Cl(-) and HCO secretion, significantly reduced mucociliary transport in the presence of ACh by 92%. Pretreatment with the anion channel blocker 5-nitro-2-(3-phenylpropylamino)benzoic acid similarly reduced mucociliary transport in ACh-treated airways by 97%. These agents did not, however, reduce ciliary beat frequency. Luminal application of benzamil to block liquid absorption significantly attenuated the inhibitory effects of bumetanide and DMA on mucociliary transport. We conclude that anion and liquid secretion is essential for normal mucociliary transport in glandular airways. Because the CF transmembrane conductance regulator protein likely mediates Cl(-), HCO, and liquid secretion in normal glands, we speculate that impairment of gland liquid secretion significantly contributes to defective mucociliary transport in CF.
Am J Physiol Lung Cell Mol Physiol 2002 Aug
PMID:Liquid secretion inhibitors reduce mucociliary transport in glandular airways. 1211 94

The uterine endometrium of swine is comprised of luminal epithelial, glandular epithelial, and stromal cells that secrete the luteolysin, prostaglandin F(2alpha) (PGF(2alpha)), during late diestrus. However, which of these cells contribute the most to luteolytic PGF(2alpha) secretion is unknown because the cellular composition of the endometrium has not been quantified. Therefore, this study quantified the cellular composition of the endometrium on days 12 and 16 postestrus by histologic and morphometric analyses. On day 12, the endometrium consisted predominantly of stromal cells (47% of total cell quantity) and glandular epithelial cells (37%), whereas luminal epithelial cells represented only 16% of the total of the three cell types. The number of glandular epithelial cells tended to increase (P < 0.10) between days 12 and 16, such that they comprised 45% of the endometrium by day 16, while the number of stromal and luminal cells did not change and accounted for 45% and 10% of the cells, respectively. Luminal epithelial cells had a 58% greater cross-sectional area (P < 0.001) than glandular epithelial cells, whereas glandular epithelial cells had a 22% greater area (P < 0.001) than stromal cells. Glandular epithelial cells decreased (P < 0.001) in cross-sectional area between days 12 and 16, whereas the area of luminal epithelial and stromal cells remained unchanged. These results indicate that the porcine endometrium is comprised predominantly of stromal and glandular epithelial cells that are likely to contribute substantially to endometrial PGF(2alpha) secretion during luteolysis. The contribution of glandular epithelium to luteolytic PGF(2alpha) secretion probably increases during diestrus as the number of these cells increases.
Anat Rec A Discov Mol Cell Evol Biol 2003 Jan
PMID:Morphometric analysis of the uterine endometrium of swine on days 12 and 16 postestrus. 1249 90


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