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)

Sorbitol density gradient centrifugation applied to intestinal mucosa homogenates resulted in a complete separation of soluble calcium-binding protein from the bound fraction of calcium-binding protein, providing further documentation of the bound pool of calcium-binding protein. The peak of the bound calcium-binding protein was not associated with the major peaks of any of the markers used, but was associated with minor peaks of alkaline phosphatase, RNA, and glucose-6-phosphatase. Lack of association of bound calcium-binding protein with (Na+ + K+)-ATPase indicated that the bound calcium-binding protein is not on the basolateral membrane. Differential centrifugation fractionation indicated that the bound calcium-binding protein is not associated with nuclei or mitochondria. The bound calcium-binding protein also could not be detected in partially purified brush borders. Exclusion of the brush border and basolateral membranes as the location of the bound calcium-binding protein suggests an intracellular locale.
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PMID:Studies on the subcellular localization of the membrane-bound fraction of intestinal calcium-binding protein. 11 17

Vitamin D3 induction of the vitamin-D3-dependent proteins biosynthesis and certain indexes characterizing the rachitic state in animals were studied as affected by potassium orotate. Introduction of potassium orotate to the rachitogenic diet in combination with vitamin D3 is shown to normalize the processess of bone mineralization and to increase intensity of chicken growth. In duodenum mucosa with rachitis orotate normalizes the activity of alkaline phosphatase, raises the content of calcium-binding protein and stimulates the latter formation after administration of vitamin D3; orotate favours redistribution of the purine and pyrimidine nucleotides content. Radioactive orotic acid is subjected to intensive metabolism in mucosa and is converted to nucleotides of pool and RNA.
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PMID:[Effect of potassium orotate on metabolism in chickens under different provision with vitamin D3]. 21 21

Vitamin D3 in rachitic chicks stimulates calcium absorption and induces the synthesis of two pools of intestinal calcium-binding protein (CaBP), one soluble and the other membrane bound. Cortisol acetate caused a decrease in calcium absorption which was accompanied by a decrease in soluble CaBP. Cortisol was similarly effective in 1,25-dihydroxyvitamin D3-dosed chicks, suggesting that the glucocorticoid effect was not entirely due to the defective synthesis of this metabolite. Ca absorption was directly correlated with soluble CaBP and alkaline phosphatase and inversely related to the ratio of bound to soluble CaBP. It was further observed that the slope of the Ca absorption vs. soluble CaBP regression line was greater in chicks given 1,25-dihyroxyvitamin D3 compared to those given vitamin D3, and this is interpreted to mean that another factor or condition, in addition to assayed concentrations of soluble CaBP, determines the degree of calcium absorption.
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PMID:Intestinal calcium-binding protein and calcium absorption in cortisol-treated chicks: effects of vitamin D3 and 1,25-dihydroxyvitamin D3. 22 Nov 83

Potassium orotate and guanine are established to accelerate the duodenum physiological response of chickens with experimental rachitis to administration of vitamin D3 in the in vivo experiments. They stumulate the uptake and transport of calcium, increase the content of calcium-binding protein and affect the activity of alkaline phosphatase. Guanine is a more effective stimulator as compared to orotate. A rise in the calcium uptake in the duodenum of the chicken which were given guanine started considerably earlier than the intensification of the calcium-binding protein synthesis in it. This suggests a possibility of the calcium uptake initiation by vitamin D3 through the mechanisims independent of the calcium-binding protein biosynthesis.
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PMID:[Effect of potassium orotate and guanine on calcium uptake in small intestine of chickens with different amounts of vitamin D3]. 22 28

Extracts of the calcinogenic plants Solanum malocoxylon and Cestrum diurnum stimulate phosphate absorption by the jejunum of vitamin D-deficient chicks, as determined by everted gut sac technique. Their action on cellular pathways of transepithelial phosphate transport is indistinguishable thereby from that of cholecalciferol. Increased net absorption from the lumen was due to enhanced uptake of phosphate from the luminal side, while leakage of tissue phosphate in the opposite direction was apparently unaffected. Steep serosa/mucosa concentration gradients were observed as consequence of enhanced levels of transepithelial phosphate flux in the mucosa-to-serosa direction. With respect to their stimulatory action on phosphate absorption, the calcinogenic plant factors retained their biological activity when phosphate transport was depressed by a high strontium diet. Their action in overcoming the strontium inhibition of phosphate absorption, calcium-binding protein synthesis, and alkaline phosphatase activity, was comparable to the effect of 1,25-dihydroxycholecalciferol. On the basis of these biological responses, the action of the plant factors from Solanum malacoxylon and Cestrum diurnum provides further evidence for their close resemblance to the hormonally active sterol.
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PMID:Stimulatory effect of 1,25-dihydroxycholecalciferol-like substances from Solanum malacoxylon and Cestrum diurnum on phosphate transport in chick jejunum. 70 9

Pregnant rats were treated with 44, 88 and 176 Medical Research Council munits of thyrocalcitonin (TCT) twice daily during days 10 to 21 of gestation. Nonpregnant rats received the same treatment for 12 days. Administration of TCT to the pregnant rats increased the ash and calcium content of fetal bones and decreased the phosphorus content. The diaphyses were short and contained many persisting enchondral trabeculae and a reduced number of osteoclasts. TCT reduced the fetal intestinal alkaline phosphatase activity but elevated the intestinal calcium-binding protein content. In the pregnant and nonpregnant rats, treatment with TCT resulted in hypocalcemia and hypophosphatemia, and increased the calcium-binding protein content of the duodenal mucosa. In the fetuses, the calcium-binding protein content and alkaline phosphatase activity were higher in the jejunum and ileum than in the duodenum, and were much higher than the values found in adult animals. Our findings indicate that TCT passes through the rat placenta and affects the fetal skeleton and calcium metabolism directly, resulting primarily in decreased bone resorption.
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PMID:Transplacental effects of thyrocalcitonin on intestinal calcium-binding protein, alkaline phosphatase activity and ossification of long bones in rat fetuses. 93 22

The intestinal absorption of calcium is certainly a complex process, dependent on several factors of which vitamin D, via 1,25(OH)2D3, is the major controlling hormone. The efficiency of calcium absorption is a function of calcium status and calcium need. As the body's demand for calcium increases, the process commonly termed, adaptation, is activated in which the synthesis of 1,25(OH)2D3 from precursor is increased, resulting in the stimulation of the rate of calcium absorption. The increased demand for calcium might result from the ingestion of a diet deficient in calcium, from growth, pregnancy, lactation and egg shell formation in the laying hen. Accomapanying the change in calcium absorptive efficiency are molecular modifications of the transporting enterocytes, some mentioned herein and elsewhere (Wasserman & Chandler, 1985; Wasserman, 1980; Wasserman et al., 1984). Highly correlated with the rate of calcium absorption under a wide variety of conditions is the concentration of the vitamin D-induced calcium-binding protein, calbindin-D28K (avian type) and calbindin-D9K (mammalian intestinal type). The role of calbindin-D in this transport process is not precisely known but is considered to act at the present time as a cytosolic facilitator of Ca2+ diffusion from the brush border membrane to the basolateral membrane. In addition to the induction of calbindin-D synthesis, 1,25(OH)2D3 exerts other effects on the intestinal epithelium that can have consequences on the calcium absorptive process. Some of these effects are summarized in Figure 14. Vitamin D-dependent reactions might be either direct effects of 1,25(OH)2D3 or indirect effects due to elevated intracellular Ca2+ concentrations. These include changes in the fluidity of the brush border membrane, an increase in microvillar alkaline phosphatase-low affinity Ca-activated ATPase activity, an association of calmodulin with the 105 kD brush border cytoskeletal protein and, following calbindin D synthesis, the binding of calbindin D to a 60 kD brush border protein and to microtubules. The latter has been suggested to be related to the proposed transfer of Ca2+ by an endocytotic-exocytotic mechanism. In addition, a vitamin D-dependent intestinal membrane calcium-binding protein has been identified (Kowarski & Schachter, 1980). Playing into this multi-component system is a stimulation of cyclic nucleotide synthesis by 1,25(OH)2D3 which, through activation of cyclic nucleotide-dependent protein kinases, might modify membrane Ca2+ "channels" by phosphorylation reactions.4+ Intracellular organelles, i.e., the endoplasmic reticulum, mitochondria, the Golgi apparatus, are potent sequesters of Ca2+ and could contribute to the protection of the cell from excessively high Ca2+ concentrations by transiently storing absorbed Ca2+.
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PMID:On the molecular mechanism of intestinal calcium transport. 254 94

Epidermal growth factor (EGF) has been reported to increase intestinal calcium absorption in suckling rats. The mechanism of this effect is unknown, as are the roles of vitamin D-dependent and independent pathways. The present studies were undertaken to investigate the ability of EGF to accelerate the postnatal induction of the vitamin D-dependent intestinal calcium-binding protein, calbindin-D9k. Subcutaneous administration of EGF increased duodenal calbindin-D9k in suckling rats by more than 100% (P less than 0.001). The effect of EGF was not seen in older weaned animals or when EGF was given to suckling rats by gavage. Administration of EGF simulated the changes of normal development. 1) It increased calbindin-D9k, and the effect was greater in proximal than distal duodenum. 2) EGF increased alkaline phosphatase activity to the same extent in proximal and distal duodenum. 3) EGF increased sucrase more markedly in distal than in proximal epithelium. Maximal and half-maximal effects of EGF on each of these proteins were observed at twice daily doses of 0.1 and 0.04 microgram/g BW, respectively. 4) EGF at the maximally effective dose produced a small (30%) but statistically significant (P less than 0.005) increase in serum 1,25-dihydroxyvitamin D. 5) Most importantly, EGF treatment resulted in a 2-fold increase in intestinal 1,25-dihydroxyvitamin D receptors (VDR) in the proximal segments of the small intestine (P less than 0.001). EGF effects on calbindin-D9k and VDR were specific for the intestine, as EGF did not change kidney calbindin-D9k or kidney VDR. Thus, EGF was able to prematurely initiate a complex series of molecular changes that occur during normal development. The mechanism of EGF's action to stimulate calcium absorption appears to involve a maturation effect on the vitamin D-dependent pathway.
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PMID:Epidermal growth factor increases intestinal calbindin-D9k and 1,25-dihydroxyvitamin D receptors in neonatal rats. 254 9

Intestinal calcium-binding protein (CaBP) (molecular weight 10,000) was measured by a specific enzyme-linked immunoadsorbent assay in duodenal biopsies of 94 patients (aged 20-89 years). The patients were examined for complaints of upper abdominal dyspepsia, but no significant pathology was found by gastroduodenoscopy. The median amount of CaBP in duodenal biopsies was 6.0 micrograms/mg of cytosolic protein with a coefficient of variation of 0.6. No change in the amount of CaBP per mg of cytosolic protein was observed with age. A significant correlation (P less than 0.001) was found between the concentration of CaBP and s-1,25-dihydroxyvitamin D (1,25(OH)2D). The amount of CaBP per mg of cytosolic protein did not correlate with immunoreactive parathyroid hormone in serum, and no relation between CaBP and the specific activity of alkaline phosphatase of the mucosal biopsies was found. The results of the present study show a wide variation in the amount of the 10 kDa CaBP in duodenal biopsies of humans and no change with age. Further, a correlation between s-1,25(OH)2D and CaBP was found.
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PMID:Calcium-binding protein in human duodenal biopsies. 313 85

A highly efficient immunoscreening procedure has been developed to isolate cDNA clones to the calcium-binding protein (CaBP) of the chick embryonic chorioallantoic membrane (CAM). A library of total CAM cDNA was constructed using the expression plasmid vector, pUC 19. Bacterial clones containing plasmids with CaBP cDNA inserts were detected immunohistochemically based on their expression of hybrid CaBP protein sequences. For immunodetection, nitrocellulose bacterial colony replicas were treated with specific antibodies to the CaBP followed by incubation with Staphylococcus aureus Protein A conjugated with alkaline phosphatase (AP) which served as a secondary immunoreagent. Positive clones were then histochemically identified based on AP enzyme activity. The identity of the immunopositive clones was further verified by in vitro translation of mRNA selected by hybridization to the cloned cDNA. The AP-based immunoscreening procedure yields stable reaction products with relatively low background, and should find general application for isolating specific cDNA clones from expression cDNA libraries.
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PMID:Alkaline phosphatase conjugated protein A as a sensitive reagent to immunoscreen an expression cDNA plasmid library: isolation of cDNA to the calcium-binding protein of the chick embryonic chorioallantoic membrane. 382 19


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