Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P50583 (asymmetrical)
 12,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Low-temperature difference spectra of gradient-purified mitochondria of Acanthamoeba castellanii reveal the presence of cytochromes b-555, b-562 and c-549, with a-type cytochromes having a broad asymmetrical maximum at 602 nm; these components were also observed in specta of whole cells. 2. The a-type cytochromes are unusual in that they have split Soret absorption maxima (at 442 and 449 nm) and an uncharacteristic CO difference spectrum. 3. CO difference spectra of whole cells and 'microsomal' membranes show large amounts of cytochrome P-420 compared with cytochrome P-450. 4. Difference spectra in the presence of cyanide indicate the presence of an a-type cytochrome and two cyanide-reacting components, one of which may be cytochrome a3. 5. Whole-cell respiration in a N2/O2 (19:1) atmosphere was decreased by 50%, suggesting the presence of a low-affinity oxidase. This lowered respiration is inhibited by 50% by CO, and the inhibition is partially light-reversible; photochemical action spectra suggest that cytochrome a3 contributes to this release of inhibition. Other CO-reacting oxidases are also present. 6. The results are discussed with the view that cytochrome a3 is present in A. castellanii, but its identification in CO difference spectra is obscured by other component(s).
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PMID:The cytochromes of Acanthamoeba castellanii. 59 58

Vacuolar ion channels were characterized after reconstitution into planar lipid bilayers. (1) Channel activity was observed after incorporation of tonoplast-enriched microsomal membranes, purified tonoplast membranes or of solubilized tonoplast proteins. (2) Channels of varying single-channel conductances were detected after reconstitution. In symmetrical 100 mmol l-1 KCl, conductances between 1 and 110 pS were frequently measured; the largest number of independent reconstitution events was seen for single-channel conductances of 16-25 pS (28 experiments), 30-42 pS (26), 49-56 pS (15) and 64-81 pS (15). Channel current usually increased linearly with voltage. (3) In asymmetrical solutions, cation-, non-selective and, for the first time for the tonoplast, anion-selective channels were detected. Ca(2+)-dependent regulation of channel opening was not observed in our reconstitution system. (4) Permeability was also observed for Cl-, NO3-, SO4(2-) and phosphate. (5) After fractionation of tonoplast proteins by size exclusion chromatography, ion channel activity was recovered in specific fractions. (6) Some of these fractions catalyzed sulfate transport after reconstitution into liposomes. The results suggest that different channels are active at the tonoplast membrane at a larger number than has been concluded from previous work.
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PMID:Reconstitution of vacuolar ion channels into planar lipid bilayers. 137 79

1. The aglycone specificity of hepatic microsomal glucuronidation was compared under uniform conditions in a fish, Pleuronectes platessa and a mammal, Rattus norvegicus, representative of the most primitive and advanced vertebrate classes. 2. Both species exhibited comparable UDP-glucuronosyltransferase (UDPGT) activity towards planar phenolic substrates (1-naphthol, 4-nitrophenol); however, plaice activity towards bulky non-planar substrates such as (-)-morphine was either 200-fold lower, or for an arylacetic acid (RS-2-phenylpropionic acid) and an aryloxyacetic acid (clofibric acid) non-detectable. 3. Conjugation of the endogenous substrates, bilirubin and steroids were 4- to 40-fold lower in the plaice than in the rat. Whilst both species formed diglucuronides of the asymmetrical bilirubin IX alpha, they displayed a reciprocal preference for the initial esterification, conjugation of the C-8 side chain predominating in the rat and of C-12 in the fish. 4. Immunoblot analysis using two polyclonal antisera preparations raised against rat UDPGTs demonstrated the presence of multiple weakly cross-reacting polypeptides in fish microsomes indicative of multiple isoforms and conservation of common structural motifs over more than 350 million years since evolutionary divergence of the mammals.
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PMID:Functional and immunochemical comparison of hepatic UDP-glucuronosyltransferases in a piscine and a mammalian species. 161 46

The acylation of 1-acyl-glycerophosphocholine is an important mechanism for the maintenance of the asymmetrical distribution of acyl groups in phosphatidylcholine. The majority of acyl-CoA:1-acyl-glycerophosphocholine acyltransferase is located in the microsomal fraction. In this study, the rat liver microsomes were incubated with various detergents, and the solubilized enzyme was separated from the remainder by centrifugation. Sodium cholate, sodium deoxycholate and octylglucopyranoside caused the solubilization of 14-25% of the enzyme activity. The acyl specificity of the solubilized enzyme was similar to the insoluble enzyme, indicating that there was no selective solubilization of any acyl specific acyltransferase. The solubilized enzyme did not display any lipid requirement, and its activity was inhibited by phosphatidylcholine, phosphatidylethanolamine and 1,2-diacylglycerol. Kinetic studies with varying concentrations of acyl-CoAs revealed that the inhibition by 1,2-diacylglycerol was essentially uncompetitive. The modulation of acyltransferase activity by 1,2-diacylglycerol may be an important mechanism for controlling the acylation of lysophosphatidylcholine.
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PMID:Solubilization and modulation of acyl-CoA:1-acyl-glycerophosphocholine acyltransferase activity in rat liver microsomes. 173 43

The enzymatic transfer of the sugar portion from UDP-N-acetylgalactosamine to pyridylamino (PA) lacto-N-fucopentaose I (Fuc alpha 1-2Gal beta 1-3GlcNAc beta 1-4Glc-PA) was detected by high-performance liquid chromatography. Separation of the fluorescent product from the fluorescence-labeled acceptor was achieved within 10 min by reversed-phase high-performance liquid chromatography. Rat stomach enzyme activity was detected in the microsomal fraction from antrum but not corpus. Ohara et al. (1986, Comp. Biochem. Physiol. 83B, 273-275) reported that the N-acetylgalactosamine content in antrum mucin was greater than that in corpus mucin and antrum mucin had strong blood group A activity. The prominent asymmetrical distribution of the enzyme detected here well supports these findings. The elution position of the fluorescent product was the same as that of the product formed by the action of type A human serum toward the acceptor. Its hydrolysis by alpha-N-acetylgalactosaminidase yielded the acceptor. It is thus evident that the detected enzyme is the same as that producing the blood group A structure.
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PMID:Detection of UDP-N-acetylgalactosamine-oligosaccharide N-acetylgalactosaminyltransferase activity in rat stomach and human serum by high-performance liquid chromatography. 314 99

Hepatic glucuronidation of the asymmetrical natural bilirubin molecule results in formation of two different positional isomers, bilirubin C-8 monoglucuronide and bilirubin C-12 monoglucuronide. In view of the existence of multiple isoforms of UDPglucuronyltransferase, which is the microsomal enzyme system responsible for bilirubin esterification, we performed kinetic analysis of microsomal glucuronidation of bilirubin and a number of its structural congeners to determine whether synthesis of the two monoglucuronide isomers involved two distinct substrate-binding sites or reflected two different modes of binding to a single catalytic site. Both isomers were found in all tested species (man, rat, guinea pig, sheep), but there were marked species differences in the C-8/C-12 ratio of monoglucuronide found in bile or formed by liver microsomes. Correspondence between in vivo and in vitro results for such regioselectivity of glucuronidation was excellent in each species. On the basis of our results of kinetic analysis of bilirubin esterification at variable pigment substrate concentrations and inhibition studies with alternative substrates, we postulate that both natural monoglucuronide isomers are synthesized at a single binding site. Possible mechanisms responsible for the markedly regioselective esterification of bilirubin by rat and sheep liver were investigated by study of glucuronidation of selected structural analogues of the pigment. Our results do not support explanations of regioselectivity of bilirubin glucuronidation in terms of (i) preferential binding of either the C-8- or C-12-containing dipyrrolic half of the asymmetrical bilirubin molecule or (ii) enantioselective complexation of bilirubin UDPglucuronyltransferase to one of the two chirality enantiomers of intramolecularly hydrogen-bonded bilirubin.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:On the binding of bilirubin and its structural analogues to hepatic microsomal bilirubin UDPglucuronyltransferase. 368 61

The in vitro incorporation of cytochrome b5 into purified plasma membranes was investigated by biochemical and immunological methods. Plasma membrane preparations incorporated three times less cytochrome b5 than did microsomal preparations; 60% of this cytochrome b5 could not be reduced by the NADH-cytochrome b5 reductase and considered as being bound to the plasma membrane. The morphological observations made after the immunochemical labeling of cytochrome b5 clearly showed a good but asymmetrical distribution of the ferritin labeling: only the inner face of the plasma membrane incorporated cytochrome b5. These results are discussed with respect to theories which concern the subcellular membrane relationships in the cell.
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PMID:The binding of cytochrome b5 to plasma membranes of rat liver: its implication for membrane specificity and biogenesis. 737 3

The phospholipid composition of rat urinary transitional epithelium (TE) and the fatty acid composition of microsomal, mitochondrial, cytosolic, and plasma membrane (PM) subcellular fractions were investigated. PM marker enzymes and electron microscopy analysis were used to characterize the PM fraction, which showed a distinctive lipid composition compared to the general profile of PM from different sources. The levels of cholesterol and sphingomyelin were not enriched in the PM fraction; on the other hand, the increased amounts of glycosphingolipids and phosphatidylserine, and the decreased level of phosphatidylcholine followed the general features of a PM profile. This differential PM lipid composition may reflect the unique morphology of this mammal TE, consisting of concave plaques with an asymmetrical membrane unit. The distribution of the double bond across the PM indicated a higher unsaturation of the inner relative to the outer part of the PM hemileaflet. In addition, the presence of 20:3n-9 nonessential fatty acid in a normal TE may represent a characteristic fatty acid metabolism of this epithelium.
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PMID:Lipid and fatty acid composition of different fractions from rat urinary transitional epithelium. 983 82

A 54-year-old man of Persian origin presented to our department with a 1-year history of ulcers on the right leg that had been unresponsive to numerous topical treatments, accompanied by lymphedema of the right leg. Medical history included hypergonadotropic hypogonadism, which had not been further investigated. He was treated for 20 years with testosterone IM once monthly, which he stopped a year before the current hospitalization for unclear reasons. The patient reported no congenital lymphedema. Physical examination revealed two deep skin ulcers (Figure 1) on the right leg measuring 10 cm in diameter with raised irregular inflammatory borders and a boggy, necrotic base discharging a purulent hemorrhagic exudate. Bilateral leg pitting edema and right lymphangitis with lymphadenitis were noted. He had low head hair implantment, sparse hair on the body and head, hyperpigmentation on both legs, onychodystrophia of the toenails (mainly the large toe and less prominent on the other toes), which was atrophic lichen-planus-like in appearance and needed no trimming (Figure 2), normal hand nails, oral thrush, and angular cheilitis. Other physical findings were gynecomastia, pectus excavatum, small and firm testicles, long extremities, asymmetrical goiter, systolic murmur 2/6 in left sternal border, and slow and inappropriate behavior. The patient's temperature on admission was 39 degrees C. Blood cultures were negative for bacterial growth. Results of laboratory investigations included hemoglobin (11.2 g/dL), hematocrit (26.8%), normal mean corpuscular volume and mean corpuscular hemoglobin volume, and red blood cell distribution width (16%). Blood smear showed spherocytes, slight hypochromia, anisocytosis, macrocytosis, and microcytosis. Blood chemistry values were taken for iron (4 micro g/dL [normal range 40-150 micro g/dL]), transferrin (193 mg/dL [normal range 220-400 mg/dL]), ferritin (1128 ng/mL [normal range 14-160 ng/mL]), transferrin saturation (1.5% [normal range 20%-55%]), serum folate (within normal limits), and vitamin B12 (within normal limits). Direct Coombs' test equaled positive 2 + IgG. All these values indicated anemia of chronic diseases combined with hemolytic anemia. Further blood work-up tested antinuclear antibody (positive <1:80 homogeneous pattern), rheumatoid factors (143 IU/mL [positive >8.5 IU/mL]), C-reactive protein (286 mg/L [normal range 0-5 mg/L]), anticardiolipin IgM antibody (9.0 monophosphoryl lipid U/mL [normal range 0-7.00 MPL U/mL]) and antithrombin III activity (135% [normal range 74%-114%]). Results of other blood tests were within normal limits or negative, including lupus anticoagulant, beta2 glycoprotein, anticardiolipin IgG Ab, anti-ss DNA Ab, C3, C4, anti-RO, anti-LA, anti-SC-70, anti-SM Ab, P-ANCA, C-ANCA, TSH, FT4, anti-T microsomal, antithyroglobulin, protein C activity, protein S free, cryoglobulins, serum immunoelectrophoresis, VDRL, hepatitis C antibodies, hepatitis B antigen, and human immunodeficiency virus. Endocrinological work-up examined luteinizing hormone (22.9 mIU/mL [normal range for adult men 0.8-6 mIU/mL]), follicle stimulating hormone (49.7 mIU/mL [normal range for adult men 1-11 mIU/mL]), testosterone (0.24 ng/mL [normal range for adult men 2.5-8.0 ng/mL]), bioavailable testosterone (0.02 ng/mL [normal range for adult men >0.6 ng/mL]), and percent bioavailable test (8.1% [normal value >20%]). These results indicate hypergonadotropic hypogonadism. Plasminogen activator inhibitor 1 was 6 U (normal value 5-20 U/mL). Karyotyping performed by G-banding technique revealed a 47 XXY karyotype, which is diagnostic of Klinefelter's syndrome. Doppler ultrasound of the leg ulcers disclosed partial thrombus in the distal right femoral vein. X-rays and bone scan displayed osteomyelitis along the right tibia. Histological examination of a 4-mm punch biopsy from the ulcer border revealed hyperkeratosis, acanthosis, hypergranulosis, and mixed inflammatory infiltrate containing eosinophils compatible with chronic ulcer. Multiple vessels were seen, compatible with a healing process. Direct immunofluorescence of the biopsy revealed granular IgM in the dermo-epidermal junction. Indirect immunofluorescence was negative. Thyroid function tests showed normal thyroid stimulating hormone and free throxine4. Multinodular goiter was seen on thyroid scan and ultrasound. Thyroid fine needle aspiration was compatible with multinodular goiter (normal follicular cells, free colloid, macrophages with pigment). IV treatment with amoxicillin-clavulanic acid 1 g t.i.d. was administered for 2 weeks, with a decrease in temperature and normalization of the leukocyte level. Oral antibiotic treatment with amoxicillin-clavulanic acid was continued for 10 more days, followed by 25 days of ciprofloxacin for the osteomyelitis. Local treatment included saline soakings followed by application of Promogran (Johnson & Johnson, New Brunswick, NJ) and Kaltostat (ConvaTec Ltd., a Bristol-Myers Squibb Company, New York, NY) with slight improvement. At the same time, the patient was treated with warfarin sodium due to deep vein thrombosis under international normalized ratio 2-3. The patient was treated with IM testosterone once monthly for 1 year, which resulted in a reduction in the diameter and depth of the leg ulcers (Figure 3). Blood tests were not performed for follow-up of the immune state.
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PMID:Klinefelter's syndrome presenting with leg ulcers. 1536 65

To better comprehend the role of gill ion regulatory mechanisms, the modulation by Na(+), K(+), NH(4)(+) and ATP of (Na(+), K(+))-ATPase activity was examined in a posterior gill microsomal fraction from the hermit crab, Clibanarius vittatus. Under saturating Mg(2+), Na(+) and K(+) concentrations, two well-defined ATP hydrolyzing sites were revealed. ATP was hydrolyzed at the high-affinity sites at a maximum rate of V=19.1+/-0.8 U mg(-1) and K(0.5)=63.8+/-2.9 nmol L(-1), obeying cooperative kinetics (n(H)=1.9); at the low-affinity sites, hydrolysis obeyed Michaelis-Menten kinetics with K(M)=44.1+/-2.6 mumol L(-1) and V=123.5+/-6.1 U mg(-1). Stimulation by Na(+) (V=149.0+/-7.4 U mg(-1); K(M)=7.4+/-0.4 mmol L(-1)), Mg(2+) (V=132.0+/-5.3 U mg(-1); K(0.5)=0.36+/-0.02 mmol L(-1)), NH(4)(+) (V=245.6+/-9.8 U mg(-1); K(M)=4.5+/-0.2 mmol L(-1)) and K(+) (V=140.0+/-4.9 U mg(-1); K(M)=1.5+/-0.1 mmol L(-1)) followed a single saturation curve and, except for Mg(2+), obeyed Michaelis-Menten kinetics. Under optimal ionic conditions, but in the absence of NH(4)(+), ouabain (K(I)=117.3+/-3.5 mumol L(-1)) and orthovanadate inhibited up to 67% of the ATPase activity. The inhibition studies performed suggest the presence of F(0)F(1), V- and P-ATPases, but not Na(+)-, K(+)- or Ca(2+)-ATPases as contaminants in the gill microsomal preparation. (Na(+), K(+))-ATPase activity was synergistically modulated by NH(4)(+) and K(+). At 20 mmol L(-1) K(+), a maximum rate of V=290.8+/-14.5 U mg(-1) was seen as NH(4)(+) concentration was increased up to 50 mmol L(-1). However, at fixed NH(4)(+) concentrations, no additional stimulation was found for increasing K(+) concentrations (V=135.2+/-4.1 U mg(-1) and V=236.6+/-9.5 U mg(-1) and for 10 and 30 mmol L(-1) NH(4)(+), respectively). This is the first report to detail ionic modulation of gill (Na(+), K(+))-ATPase in C. vittatus, revealing an asymmetrical, synergistic stimulation of the enzyme by K(+) and NH(4)(+), as yet undescribed for other (Na(+), K(+))-ATPases, and should provide a better understanding of NH(4)(+) excretion in pagurid crabs.
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PMID:A kinetic study of the gill (Na+, K+)-ATPase, and its role in ammonia excretion in the intertidal hermit crab, Clibanarius vittatus. 1693 Oct 80


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