Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.4.3 (phospholipase C)
 18,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The Rho(D) antigen of red cell membranes was solubilized using ethylene-diamine tetraacetic acid (EDTA) and 2-mercaptoethanol. The solubilized antigen was partially separated from other solubilized membrane components using molecular filtration. The antigen was treated with various enzymes to learn some of the chemical characteristics. It was found that the activity of the antigen, as measured by hemagglutination inhibition, was not affected by bee venom phospholipase A, Clostridium welchii phospholipase C, calf-intestinal alkaline phosphatase, Vibrio cholerae neuraminidase, pig kidney leucine aminopeptidase, bovine pancreatic carboxypeptidase A, and pig pancreatic carboxypeptidase B. However, the proteolytic enzymes, pronase, trypsin, chymotrypsin and papain, did destroy Rho(D) activity as measured by hemagglutination inhibition. These results indicate that protein is an important part of the active determinant of the Rho(D) antigen. The experiments by other investigators have shown that lipid is important to maintain the Rho(D) activity in the intact membrane; lipid probably helps to maintain the structural conformation of the Rho(D) molecule in its natural environment. The solubilized Rho(D) molecules are apparently not dependent on lipid for their Rho(D) activity.
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PMID:Studies on the characterization of the Rho(D) antigen. 10 79

1. Alkaline phosphatase is covalently bound to bovine mammary microsomal membranes and milk fat globule membranes through linkage to phosphatidylinositol as demonstrated by the release of alkaline phosphatase following treatment with phosphatidylinositol-specific phospholipase C. 2. The release of alkaline phosphatase from the pellet to the supernatant was demonstrated by enzyme assays and electrophoresis. 3. Electrophoresis of the solubilized enzymes showed that the alkaline phosphatase of the microsomal membranes contained several isozymes, while only one band with alkaline phosphatase activity was seen in the fat globule membrane. 4. Levamisole and homoarginine were potent inhibitors of the alkaline phosphatase activities in both membrane preparations and in bovine liver alkaline phosphatase, but not in calf intestinal alkaline phosphatase.
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PMID:Alkaline phosphatase in the lactating bovine mammary gland and the milk fat globule membrane. Release by phosphatidylinositol-specific phospholipase C. 137 15

1. Considerable amounts of intestinal alkaline phosphatase (AP) were found intralumenally in all animal species investigated, i.e. calf, pig, goat, rat, mouse, guinea pig, hen and carp. The ratios between the total activity of AP found intralumenally and the total intestinal activity vary considerably. Calves and pigs show the highest, i.e. 0.77 and 0.44, respectively, while rodents have much lower ratios. Only 20-34% of the intralumenal alkaline phosphatase (IAP) of the calf and pig is soluble and not within the sediment after centrifugation at 135,000 x g for 60 min. whereas the IAP of rodents is soluble in the range of 60-72% of the total IAP. 2. For the IAP of the mucosa and chyme of calf, all criteria were found which are generally used, indicating a glycosylphosphatidylinositol (GlcPtdIns) anchor as proved by strong hydrophobicity using Triton X-114 phase partitioning, phenyl-Sepharose binding and enzyme aggregation, and the susceptibility to phosphatidylinositol-specific phospholipase C (PtdIns-PLC) and papain digestion. 3. More than 80% of the mucosa alkaline phosphatase (MAP) of the proximal part of the intestine and of the particulate fraction of IAP exhibit these criteria indicating the presence of the GlcPtdIns-anchor structure, whereas the anchor content of the soluble intralumenal enzyme decreases from the pylorus to the ileocecal junction. 4. MAP partially purified to a specific activity of 1747 IU/mg retains the anchor structure. 5. The results presented indicate that the release of large amounts of AP into the chyme is realized without splitting the GlcPtdIns anchor. The possible intralumenal function of this form of AP is discussed.
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PMID:Evidence for glycosylphosphatidylinositol anchoring of intralumenal alkaline phosphatase of the calf intestine. 164 47

The antigen detected by monoclonal antibodies reacting with human osteosarcoma-associated antigen was shown to be a phosphatidyl-inositol (PI)-glycan-anchored protein, which can be released from the cell surface by PI-specific phospholipase C-treatment. The antigen detected by 2D3 and 2H10 antibodies exhibited alkaline phosphatase activity. Both antibodies strongly reacted with bone-type alkaline phosphatase. However, importantly, immunohistochemical analysis demonstrated that 2D3 and 2H10 did not react with alkaline phosphatase present in kidney or liver. In addition, neither placental nor intestinal alkaline phosphatase was recognized by 2D3 and 2H10 antibodies. These results indicated that two monoclonal antibodies, 2D3 and 2H10, are highly specific for bone-type alkaline phosphatase and can distinguish bone alkaline phosphatase from liver alkaline phosphatase in spite of the fact that liver and bone alkaline phosphatase are encoded by the same gene.
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PMID:Detection of bone-type alkaline phosphatase by monoclonal antibodies reacting with human osteosarcoma-associated antigen. 171 40

Rat intestinal alkaline phosphatase (IAP) is unique among the brush-border membrane enzymes in that it is released bidirectionally (lumen and blood) and exists in either soluble (serum) or particulate (cellular) form. To elucidate the mechanism of membrane release, we examined the effects of phosphatidylinositol-specific phospholipase C (PtdIns-PLC) and serum anchor-specific phospholipase D (PLD) on the solubility of the various tissue forms of IAP. The "solubility" of cytosol IAP could be explained in part by intracellular PtdIns-PLC activity, detected by production of acidic IAP isomers, and by ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA)-sensitive PtdIns hydrolysis. Contamination with serum (abundant with anchor-specific PLD) was responsible for the complete or partial solubilization of IAP that was found during processing of light mucosal scrapings. Anchor-specific PLD activity was increased after fat feeding, and the IAP released did not react with antiserum that recognizes the PtdIns-PLC-released phospholipid portion of trypanosomal variable surface glycoprotein. These data are consistent with the hypothesis that, after secretion from the enterocyte bound to a phospholipid-rich membranous particle, IAP release into serum is mediated by serum anchor-specific PLD. The soluble forms of IAP in the lumen and the cytosol fraction appear to be due to a combination of endogenous PtdIns-PLC activity and anchor-specific PLD contamination that occurs during cell fractionation.
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PMID:Both tissue and serum phospholipases release rat intestinal alkaline phosphatase. 222 Oct 72

1. Dog intestinal alkaline phosphatase (IAP), an asialoglycoprotein, appeared to be a good marker for the histochemical detection of the galactose specific binding protein in cryostat sections of rat liver. 2. Binding of IAP to the receptor is optimal at neutral and slightly alkaline pH values. The binding could be inhibited by galactose and galactose containing sugars, whereas glucose and mannose did not show any effect. In contrast to fetuin itself desialylated fetuin completely inhibited IAP binding. Pretreatment of sections with phospholipase C or with trypsin inhibited IAP binding; collagenase did not show any influence. 3. The presence of the galactose-binding protein showed a distinct zonal distribution. In the area around the central vein (zone 3) the highest IAP binding capacity was found.
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PMID:A histochemical study about the zonal distribution of the galactose-binding protein in rat liver. 744 Feb 65

Two cDNAs encode rat intestinal alkaline phosphatases having completely different carboxyl-terminal peptides; one is hydrophobic and fulfills the consensus requirements for glycan phosphatidylinositol linkage, and the other is neither hydrophobic nor hydrophilic, but contains a small amino acid domain (-NSASS-) just distal to a region of 17 threonine residues. Constructs were created using 80% of the amino-terminal portion of one alkaline phosphatase and the carboxyl-terminal portions of each of the isoforms. Both of the carboxyl-terminal peptides supported glycan phosphatidylinositol linkage as demonstrated by the following criteria: 1) plasma membrane targeting in transfected COS-1 cells, 2) release of transfected alkaline phosphatase by phosphatidylinositol-specific phospholipase C, 3) appearance of the trypanosome variable glycoprotein cross-reacting determinant after phospholipase C treatment, 4) ethanolamine incorporation into newly synthesized enzyme, 5) loss of phospholipase C release after mutation of the omega and omega + 2 positions in the putative linkage site, -NSA-, and 6) evidence of surface membrane localization by immunofluorescence using antibody against rat intestinal alkaline phosphatase. These data demonstrate that a predicted hydrophobic carboxyl-terminal sequence is not essential for glycan phosphatidylinositol linkage. Moreover, because both isomers are membrane-bound, the origin of soluble enzyme in the serum is likely to arise from the action of serum phosphatidylinositol-specific phospholipase C.
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PMID:Two rat intestinal alkaline phosphatase isoforms with different carboxyl-terminal peptides are both membrane-bound by a glycan phosphatidylinositol linkage. 774 44

The role of the vitamin D-induced calcium binding protein termed calbindin-D (CaBP) in the biological response to 1,25-dihydroxyvitamin D3 was assessed by photoaffinity labeling techniques. The heterobifunctional cross-linking reagent methyl-4-azidobenzoimidate was employed for studies with the 28 KD chick intestinal calbindin-D28K. Calcium-dependent interactions were evident with purified chick intestinal CaBP-immunoglobulins and bovine intestinal alkaline phosphatase; in the absence of Ca2+ there was a greatly diminished crosslinking process. There were also at least two membrane components of chick intestinal brush border membranes, with M(R) = 60,000 and 130,000, which were photoaffinity cross-linked with CaBP in a calcium-dependent manner. Similar interactions were demonstrated following incubations of CaBP with phosphatidylinositol-specific phospholipase C (PI-PLC)-treated supernatant fractions from chick intestinal brush borders. PI-PLC was shown to release 14% of the alkaline phosphatase from chick intestinal brush borders compared to greater than 80% for rabbit and chick kidney BBM preparations. Specific interactions between CaBP and brush border membrane proteins could also be demonstrated in the absence of photoaffinity labeling by Sephadex G-150 chromatography of Triton X-100 solubilized incubations between calbindin-D28K and chick intestinal BBMS, with 17% of the radiolabelled CaBP comigrating with alkaline phosphatase activity. These studies collectively demonstrate that calbindin-D28K undergoes calcium-dependent conformational changes which alter its subsequent interactions with cellular proteins in a way consistent with other calcium-binding proteins such as calmodulin or troponin C.
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PMID:Evidence for calcium mediated conformational changes in calbindin-D28K (the vitamin D-induced calcium binding protein) interactions with chick intestinal brush border membrane alkaline phosphatase as studied via photoaffinity labeling techniques. 836 39

Mg uptake was investigated with (28)Mg by a rapid filtration procedure in rat duodenal and jejunal brush border membrane (BBM) vesicles, prepared by CaCl(2)a or MgCl(2)b differential precipitation. At 1 mM Mg, 10 s uptakes were lower in jejunal vesicles (3.5(a) or 5.5(b) nmol/10 s per mg protein) than in duodenal vesicles (11.4(a) or 13.5(b) nmol/10 s per mg protein). The equilibrated 60 min uptakes were also lower in jejunum (11.0(a) or 26.6(b) nmol/60 min per mg protein) than in duodenum (l8.8(a) or 26.6(b) nmol/60 min per mg protein). The influence of medium osmolarity on 10s and 60 min uptakes of Mg indicated that Mg was 'transported' into osmotically active spaces. The effect of Mg concentration on the 10 s uptake suggested the existence of one single mechanism of transport in the duodenum, with an apparent K(T) of 1 mM, and of two mechanisms in the jejunum, with apparent K(T) values of 0.2 and 2-5 mM. Despite different amounts of calcium and magnesium in CaCl(2) and MgCl(2) precipitated vesicles, there were no large differences in magnesium uptakes depending on the mode of preparation of the vesicles. In contrast, calcium uptakes. measured with (45)Ca, were six to nine times higher in MgCl(2) prepared jejunal vesicles, and were always much higher than magnesium uptakes measured under the same conditions. At 0.1 mM calcium concentration, calcium uptake was depressed by 0.025 mM verapamil (50 percent) and by 0.1 mM ZnCl(2)(40-75 percent), while Mg uptakes were unaffected. L-leucine or L-phenylalanine (5 mM), two inhibitors of intestinal alkaline phosphatase, decreased Mg uptake by 30 to 40 percent at 1 mM Mg, but had no significant effect at 0.1 mM, and did not affect calcium uptakes at all. A possible involvement of alkaline phosphatase in magnesium uptake was ascertained in jejunal BBM vesicles treated with phosphatidylinositol-specific phospholipase C, which partially released alkaline phosphatase from the BBM. Calcium uptakes were unaffected by the treatment, while magnesium uptakes were significantly decreased at 1 mM Mg. These results confirm that magnesium and calcium are transported by distinct mechanisms in the jejunum.
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PMID:Uptake of (28)Mg by duodenal and jejunal brush border membrane vesicles in the rat. 886 Nov 32