Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.3.1 (alkaline phosphatase)
47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Brush border membrane vesicles were isolated from rat kidney cortex by differential centrifugation in the presence of 10 mM calcium. Their properties were compared to brush border vesicles isolated by free-flow electrophoresis. By the calcium precipitation method membrane vesicles were obtained in a shorter time with a similar enrichment of brush border marker enzymes (11- to 12-fold for alkaline phosphatase and maltase), with a similarly reduced activity of the marker enzyme for basal-lateral plasma membranes and an almost identical protein composition as revealed by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. The transport properties of the two membrane preparations for D-glucose, L-phenylalanine, and phosphate are essentially the same; there is some indication for a lower sodium permeability of the vesicles prepared by the calcium precipitation method. The latter vesicles were also shown to exhibit sodium gradient stimulated uptake of L-glutamate.
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PMID:Properties of brush border vesicles isolated from rat kidney cortex by calcium precipitation. 75 88

Insulin receptor characteristics were examined in purified brush border membrane from the syncytiotrophoblast of the normal human placenta and quantified during membrane preparation. Insulin receptor concentration was enriched 10- to 15-fold in this preparation, and insulin receptor specific activity followed closely the enrichment values for microvillus plasma membrane markers, alkaline phosphatase, Ca2+- and Mg2+-ATPase, and 5'-nucleotidase during cell fractionation. Insulin receptor concentrations and marker enzyme analyses were compared in whole homogenate, mitochondrial, microsomal, and microvillus fractions, and these fractions were characterized by SDS-gel electrophoresis. Microvillus insulin receptor interactions were dependent on time, [125I]iodoinsulin concentration, protein, and unlabeled hormone concentrations. Competition studies with porcine insulin and [125I]iodoinsulin for this receptor revealed a curvilinear Scatchard plot. Insulinase was demonstrated at 37 C but was minimal at 24 C in the microvillus fraction. Electron microscopy of the microvillus membrane preparation revealed its composition to be mainly spherical closed membrane vesicles and brush border fragments. Sodium dodecyl sulfate polyacrylamide and isoelectric focusing gels of membrane fractions were compared. Actin was tentatively identified as a major microvillus membrane protein and was further fractionated: beta-Actin and gamma-actin were present in approximately equal concentrations. The localization of the insulin receptor in the microvillus brush border of the human placenta suggests that this receptor interacts with maternal, rather than fetal insulin.
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PMID:Characteristics of the microvillus brush border of human placenta: insulin receptor localization in brush border membranes. 75 22

Rat kidneys were disaggregated with 0.25% trypsin. Cell were separated by velocity sedimentation in a previously described isokinetic gradient, by isopycnic sedimentation, and by velocity sedimentation followed by isopycnic sedimetation. In some fractions from the isokinetic gradient, 71.8+/-2.4+ of the nucleated cells contained histochemically demonstrable alkaline phosphatase (HDAP); in semithin sections, 62.7+/-2.3% of these cells had brush borders. The correspondence between fractions enriched for cells with HDAP and fractions enriched for brush border suggested that HDAP might be a suitable marker for rat proximal tubule cells. These cell constituted 46.5+/-2.6% of the nucleated cells in the starting sample suspension of kidney cells, and 81.9+/-2.7% of nucleated cells in the purified fractions from the gradients. More than 98% of nucleated cells in these fractions excluded typan blue. Following isopycnin centrifugation, the purest fractions contained 87.3+/-1.5% nucleated cells with HDAP, 9.6+/-2.5% nucleated cells iwithout HDAP, and 3.1+/-2.5% red blood cells. These proximal tubule cells had densities of 1.036 to 1.052 g/ml. With rate-zonal separation followed by isopycnic separation, the purest gradient fraction contained 93.0+/-1.9% nucleated cell with HDAP, 6.0+/-2.3% nucleated cells with HDAP, and 1.0+/-0.9% red blood cells. These proximal tubule cells sedimented a density of 1.041 g/ml. More than 98% of these cells excluded trypan blue.
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PMID:Separation of proximal tubule cells from suspensions of rat kidney cells in density gradients of Ficoll in tissue culture medium. 84 13

The separation by polyacrylamide gel electrophoresis and subsequent enzymatic analysis of the components of the guinea pig intestinal brush border membrane revealed the presence of three enzyme complexes: maltase-glucoamylase, maltase-sucrase-glucoamylase and maltase-sucrase. Additional bands possessing lactase, trehalase and alkaline phosphatase activity were identified but no phlorizin hydrolase or palatinase was detectable. After exposure to strong dissociating conditions the bands possessing enzymatic activity were either absent or greatly reduced in intensity.
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PMID:Glycosidases of the guinea pig brush border membrane. 86 Dec 25

The subcellular localization of enterokinase is controversial. In this study, enterokinase was extracted from a soluble fraction and a brush border fraction of rat small intestine by differential centrifugation. The soluble fraction contained 41% of the initial enterokinase activity while the brush border fraction contained only 4.6% of the initial activity. In contrast, alkaline phosphatase monitored as a brush border marker, yielded 26.3% in the brush border fraction and only 6% in the soluble fraction. Further separation of the soluble fraction on a Sepharose 4B column revealed three peaks of enterokinase activity. One small peak (3%) of a bound enzyme (Mr, 2 - 10(6)) and two larger peaks of free enzyme (Mr, 3 - 10(5) and 9 -10). In contrast, alkaline phosphatase major fraction was in a high molecular weight peak of bound enzyme. When the brush border fraction was chromatographed only a single peak of bound enterokinase and alkaline phosphatase were found. In the lower part of the small intestine, no brush border-bound enterokinase was found, while the peak of alkaline phosphatase was the same as in the upper intestine. These data suggest that enterokinase activity in the rat intestine is mainly in a free form localized in the mucin and soluble fraction and to a negligible extent in the brush border.
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PMID:Subcellular localization of enterokinase (enteropeptidase EC 3.4.21.9) in rat small intestine. 87 77

The incorporation of [14C]glucosamine into brush border glycoproteins by human small intestinal mucosa in organ culture has been investigated. The experiments were based on the observations that (1) isolated brush border membrane fragments from cultured explants showed an unchanged pattern of protein bands and brush border enzyme activities on sodium dodecyl sulfate/polyacrylamide gels after electrophoresis and (2) the rate of overall [14C]glucosamine incorporation measured in the tissue homogenate remained constant up to 48 h. After 24 h of culture, the radioactivity peaks on gels due to incorporation of [14C]glucosamine were found exclusively in the high molecular weight region and corresponded to protein bands identified as maltase-glucoamylase, lactase, sucrase-isomaltase, enterokinase and alkaline phosphatase. Enzymatic activity could not be assigned to the three remaining labelled bands. Most of these glycoproteins were already labelled after 5 h. Newly glycosylated brush border enzymes remained predominantly associated with the brush border membrane of intact cells with little release into the medium up to 24 h.
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PMID:Biosynthesis of brush border glycoproteins by human small intestinal mucosa in organ culture. 88 74

The influence of antidiuretic hormone (ADH) and papaverine on hydroxyquinoline-induced nephropathy in rats was tested, using histotopochemistry, enzyme activity measurement and morphometric investigation. Hydroxyquinoline causes a marked increase in renal weight, the development of wedge-shaped foci with severely dilated tubule segments, and a simultaneous reduction in dehydrogenases, alkaline phosphatase, and alpha-naphthyl esterase. Both ADH and papaverine produced a significant inhibition of renal damage. The subjective findings were quantitatively confirmed by measurement of enzyme activity, using the microscope photometer, and by morphometric studies with the Leitz-Classimat (determination on the basis of the alkaline phosphatase reaction) of the surface percentage of brush border in the proximal tubules. A disturbance of the hairpin counter-current system is to be considered as the cause of the renal lesion. This disturbance is caused by hydroxyquinoline-induced impairment of Na+/K+ transport, especially in the thick ascending limb of Henle's loop. Our results show that the hydroxyquinoline nephropathy can be favourably influenced both by stimulation of water re-absorption and possibly also transepithelial Na+ transport (ADH), and by increasing the blood flow of the arteriolae rectae with a resultant lowering of the intratubular urine concentration (papaverine). The dependency of hydroxyquinoline nephropathy on the phylogenetically determined concentration capacity of the kidney, and the effective influencing of the condition by ADH and papaverine indicate the importance of the degree of efficiency of the medullary countercurrent system in the pathogenesis of this renal lesion.
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PMID:The significance of the hairpin counter-current principle in the pathogenesis of toxic kidney lesions. An investigation of the influence of antidiuretic hormone and papaverine on hydroxyquinoline nephropathy of the rat. 88 59

Plasma membrane fractions from the brush border (BBM) and antiluminal (ALM) surfaces of the dog's renal proximal tubule cell were separated using free-flow electrophoresis. Rabbits immunized with BBM rapidly produced antibody, but rabbits immunized with ALM did not respond. Indirect immunofluorescence and immunoferritin studies showed that the antibody reacts with the brush border of the proximal tubules in the normal kidney of the adult dog. It also reacts with the surface membranes of certain other absorptive and secretory epithelia, such as gall bladder, small intestine, epididymis, and lacrimal gland. The antibody has affinity for the membrane maltase without affecting its catalytic activity, but does not appear to have affinity for the membrane alkaline phosphatase or the high affinity binding site for phlorizin present in the BBM. Polyacrylamide electrophoresis of solubilized BBM showed approximately 37 protein bands and four glycoproteins. We conclude that the proximal tubule cell is immunologically polarized with respect to the distribution of antigenic proteins, and that the BBM is highly antigenic. The antigenic components appear to be high molecular weight glycoproteins present in the glycocalyx.
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PMID:Immunologic characterization of plasma membranes from the renal proximal tubule of the dog. 89 9

From an homogeneous breeding one can occasionnally select a rat (rat +) showing an exceptionally high calcium absorption. For such a rat, high calcium absorption is accompained by a similar high alkaline phosphatase activity in the ileum. This fact was shown in six different assays. For rat +, this enzymatic excitation seems specific for intestinal phosphatase. Other characteristic enzymes of brush border such as maltase, invertase and leucylaminopeptidase do not vary much. Only slight modifications of phosphatase activity were observed in other organs or tissues: plasma, kidney, bone. The variations for liver are more important but unsignificant. The high calcium absorption is related to alkaline phosphatase. It is observed atdifferent steps of the preperation and can be increased by sorbitol, this last property being characteristic of the enzyme. The aptitude of a rat + for high calcium absorption is only momentany. When it goes back to usual calcium utilization, intestinal mucosa shows a normal phosphatasic activity.
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PMID:[New correlation between absorption of calcium and activity of intestinal alkaline phosphatases]. 93 Dec 62

1. The specific activities of aminopeptidase, alkaline phosphatase and aldolase isozymes were measured in homogenates of kidneys taken at different stages of ontogeny. The cellular localization of these enzymes was studied in cryostat tissue sections using substrate linked assays for aminopeptidase and alkaline phosphatase and the mixed aggregation immuno-cytochemical technique for aldolase isozymes; local enzyme concentrations were estimated photometrically. 2. The presence of both aldolase-A and aldolase-B was demonstrated in all metanephrogenic cells (and at still higher concentrations in collecting tubule cells) of the rat fetus 16 days after conception and in the undifferentiated cells of the neogenetic zone of kidney up to 8 days after birth; no aminopeptidase or alkaline phosphatase could be found in these cells. 3. Measurements made on stained tissue sections show that the shift towards aldolase-B, seen in homogenate analyses, is due to a change in the relative amounts of proximal tubules. No evidence was seen for repression in the synthesis of aldolase-A or aldolase-B monomers in the different kidney cells during ontogeny. 4. Two transitions in the mode of nephron differentiation were observed: one was shortly after birth, the other followed weaning. Before the first transition the concentrations of the enzymes increased to different degrees, such that the enzymes reached concentrations comparable with those as in the cells of adult rats by 2 to 4 days post partum. After the second transition proximal tubule size and specific activity of brush border membrane enzymes increased 3 fold. In contrast, the distal tubules did not increase significantly in size, but their aldolase-A concentration increased 3 fold. 5. Evidence based on enzyme quantification and morphometry in kidney sections is presented to demonstrate that the proximal tubule cells show functional adaptation by two independent mechanisms: specific amplification of gene expression and hypertrophy. In contrast, the distal tubule shows functional adaptation only by specific amplification of gene expression.
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PMID:The differentiation of proximal and distal tubules in the male rat kidney: the appearance of aldolase isozymes, aminopeptidase and alkaline phosphatase during ontogeny. 95 79


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