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)

Placental alkaline phosphatase (placental ALP, PLAP) and germ-cell ALP (GCAP, also known as placental-like ALP), expressed in gonadal cancer tissues, are potential tumor markers. Four monoclonal antibodies, raised against PLAP and recognizing different epitopes, were selected to study the influence of the following variables on the accuracy of PLAP and GCAP measurement: phenotype, molecular form, and glycation pattern of PLAP and GCAP; incubation temperature; and interferences by serum during immunobinding. Nine GCAP phenotypes were identified, interacting with each antibody at a lower affinity than was seen for the more common PLAP phenotypes. Antibody affinity is higher for the free hydrophilic dimeric forms of PLAP and GCAP, and is not influenced by the degree of glycation. In serum or tissue extracts, measurement of PLAP or GCAP is most nearly accurate when immunoincubations are performed at 37 degrees C, with use of antibodies 327 and 7E8, respectively. In addition, correct measurements are achieved only when, during immunobinding, serum is incubated with an equal volume of deoxycholate (9 g/L final concentration).
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PMID:Enzyme immunoassay of human placental and germ-cell alkaline phosphatase in serum. 169 76

We have developed hybridization probes that clearly distinguish the RNA transcripts of the two closely related human heat-stable alkaline phosphatase genes. RNA from the PLAP-1 gene, encoding the term placental alkaline phosphatase, is the predominant transcript in placenta from 8 weeks to term. Transcripts from the PLAP-2 gene, encoding the germ-cell or PLAP-like enzyme, are also detectable in the placenta, but at no more than 2 per cent the level of PLAP-1 transcripts.
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PMID:Trace expression of the germ-cell alkaline phosphatase gene in human placenta. 172 15

Human placental and germ cell alkaline phosphatases (PLAP and GCAP, respectively), are characterized by their differential sensitivities to inhibition by L-leucine, EDTA, and heat. Yet, they differ by only 7 amino acids at positions 15, 67, 68, 84, 241, 254, and 429 within their respective 484 residues. To determine the structural basis and the amino acid(s) involved in these physicochemical differences, we constructed three GCAP mutants by site-directed mutagenesis and six GCAP/PLAP chimeras and then expressed these alkaline phosphatase mutants in COS-1 cells. We report that the differential reactivity of PLAP and GCAP depends critically on a single amino acid at position 429. GCAP with Gly-429 is strongly inhibited by L-leucine, EDTA, and heat, whereas PLAP with Glu-429 is resistant. By substituting Gly-429 of GCAP with a series of amino acids, we demonstrate that the relative sensitivities of these mutants to L-leucine, EDTA, and heat inhibition are, in general, parallel. Mutants in the order of resistance to these treatments are: Glu (most resistant), Asp/Ile/Leu, Gln/Val/Lys, Ser/His, and Arg/Thr/Met/Cys/Phe/Trp/Tyr/Pro/Asn/Ala/Gly (least resistant). However, the Ser-429 and His-429 mutants were more resistant to EDTA and heat inhibition than the wild-type GCAP, but were equally sensitive to L-leucine inhibition. Structural analysis of mammalian alkaline phosphatase modeled on the refined crystal structure of Escherichia coli alkaline phosphatase indicates that the negative charge of Glu-429 of PLAP, which simultaneously stabilizes the protein as a whole and the metal binding specifically, probably acts through interactions with the metal ligand His-320 (His-331 in E. coli alkaline phosphatase). Replacement of codon 429 with Gly in GCAP leads to destabilization and loosening of the metal binding. The data suggest that the natural binding site for L-leucine may be near position 429, with the amino and carboxyl groups of L-leucine interacting with bound phosphate and His-432 (His-412 in E. coli alkaline phosphatase), respectively.
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PMID:Mutation of a single amino acid converts germ cell alkaline phosphatase to placental alkaline phosphatase. 193 59

The significance of the PLAP (Placental alkaline phosphatase)/PLAP-like isozyme as tumour marker in relation to CA 125 and TPA for the monitoring of patients with malignant ovarian epithelial tumours was evaluated. Of all patients (n = 85), 40% had all three markers elevated. CA 125 being the most sensitive (60%), and the PLAP/PLAP-like isozyme and TPA both 40%. A tendency to certain tumour marker patterns of these three antigens in serum can be seen with regard to histopathology. Serous and anaplastic adenocarcinomas usually have all three markers moderately elevated, mucinous and mesonephric adenocarcinomas both have low incidences and low average levels of all three markers. Endometrioid and non-mucinous adenocarcinomas are often associated with high levels of the PLAP/PLAP-like isozyme and CA 125, while TPA shows moderate elevation. The PLAP/PLAP-like isozyme is positively correlated to tumour burden and the outcome of the disease. It may provide additional information on CA 125 in the monitoring of patients with ovarian cancer.
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PMID:Placental alkaline phosphatase (PLAP)/PLAP-like alkaline phosphatase as tumour marker in relation to CA 125 and TPA for ovarian epithelial tumours. 209 51

The steady-state levels of mRNAs encoding alkaline phosphatase isoenzymes were examined in two human breast carcinoma cell lines. MDA-MB-157 cells expressed the phenotypic breast alkaline phosphatase and BT20 cells expressed the nonphenotypic placental alkaline phosphatase isoenzyme, frequently reexpressed in neoplasms. Dexamethasone (DEX), which elicits a general effect on phosphatase expression, and 1,25-dihydroxy vitamin D3 (1,25(OH)2D3), a promoter of cell differentiation that correspondingly effects embryonic phosphatase expression, were chosen as perturbing agents for these experiments. RNA blot analysis showed a single RNA species of approximately 2.6 kb under all treatment conditions in BT20 cells and a single RNA species of 2.6 kb under each condition in MDA-MB-157 cells. The results showed that the expression of both the AP isoenzyme mRNA phenotypic of breast produced by MDA-MB-157 cells and the embryonic alkaline phosphatase isoenzyme (PLAP) mRNA produced by BT20 cells was increased by treatment with DEX. By comparison 1,25(OH)2D3 caused an increase in the tissue-unspecific AP mRNA in the MDA-MB-157 cells, but caused a decrease in PLAP mRNA levels in BT20 cells. The level of each isoenzyme mRNA species is altered by either hormone in a dose- and time-dependent manner in both cell lines. In BT20 cells, treatment with cycloheximide showed that ongoing protein synthesis is not required to potentiate the PLAP mRNA response to DEX, but is required for the action of 1,25(OH)2D3. However, protein synthesis is required for the action of both hormones in the MDA-MB-157 cells which make the breast phenotypic AP. These data demonstrate that the DEX- and 1,25(OH)2D3-regulated expression of both of these alkaline phosphatase isoenzymes occurs via a complex mechanism involving control of mRNA abundance, not translational control of constant message levels.
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PMID:A difference in the regulation of mRNA expression between the phenotypic and the embryonic alkaline phosphatase genes in human cancer cells. 233 89

The clinical course of colorectal carcinoma may be monitored by tumor markers such as carcinoembryonic antigen (CEA), carcinoma antigen (CA) 19-9 and CA-50. Alkaline phosphatase isozymes were previously used to study the clinical course of testicular and gynecologic tumors. In this study we investigated 8 patients with advanced colorectal carcinoma. Their sera were analyzed for the tumor markers CEA, CA 19-9, CA-50 and three alkaline phosphatase isozymes: the nonspecific liver isozyme LAP, the intestinal isozyme IAP and the placental isozyme PLAP. Rising levels of CEA, CA 19-9 and CA-50 were seen as expected, and PLAP also showed rising levels during tumor progression. LAP remained elevated. This indicates an association between progression of colorectal carcinoma and a raised serum content of alkaline phosphatase isozymes.
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PMID:Significance of alkaline phosphatase isozymes in the monitoring of patients with colorectal carcinoma. 281 31

A human term (third trimester) placental alkaline phosphatase (PLAP; EC 3.1.3.1) cDNA was isolated from a human placental lambda gt11 cDNA library. The expression library was screened by using rabbit antibodies against PLAP and oligonucleotide probes. DNA sequence analysis of a positive clone with an insert of 2.7 kilobase pairs allowed us to predict the complete amino acid sequence of PLAP (530 residues), which coincided with the reported 42 N-terminal amino acid sequence of PLAP except at position 3. Contrary to the previous supposition that there was no amino acid sequence homology between PLAP and Escherichia coli alkaline phosphatase (471 residues), we found 30% overall homology, with regions of strong homology including the putative active site and the metal-binding sites. The 44-residue C-terminal extension of PLAP has a stretch of 17 hydrophobic amino acids, which presumably anchors the protein to the plasma membrane, a change perhaps necessary for the transition from a bacterial periplasmic enzyme to a mammalian membrane-associated enzyme. We have also localized PLAP-related DNA sequences mainly on chromosome 2 and to a lesser degree on chromosome 17. It seems likely therefore that the PLAP gene resides on chromosome 2 and other member(s) of the alkaline phosphatase family may exist (on this chromosome and) on chromosome 17.
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PMID:Cloning, sequencing, and chromosomal localization of human term placental alkaline phosphatase cDNA. 300 17

In 1930 the determination of serum alkaline phosphatase in patients with bone or liver disease ushered in the era of clinical enzymology. The association of elevated (bone) alkaline phosphatase in serum of patients with osteogenic sarcoma was the first evidence that tumor cells themselves produced the enzyme. It became clear, however, in the 1960s that the serum alkaline phosphatase was not a single enzyme but consisted of a family of isozymes originating from liver, bone, intestine, and placenta. This was a consequence of the introduction of a combination of electrophoretic separations, heat inactivation, and organ-specific amino acid inhibitors. This combination of measurements made possible the demonstration of a serum alkaline phosphatase of lung cancer origin, as confirmed by the histochemical visualization in lung cancer of the Regan Isozyme (placental alkaline phosphatase-PLAP). At present, the measurement of PLAP has its greatest utility as a tumor marker in seminoma and ovarian cancer. A PLAP-like isozyme in normal testis and ovary is expressed in these and other neoplasias and appears to be related to rare alleles of placental alkaline phosphatase. Current studies have utilized a panel of monoclonal antibodies to detect useful epitopes that suggest that PLAP and PLAP-like isozymes are coded by different genes. The PLAP gene has now been cloned and sequenced by Millan and others. This fundamental new information is providing a base line that will make it possible to explain the overlapping specificities of intestinal and placental isozymes, the degree of uniqueness of the PLAP-like isozyme, the precise mechanism of uncompetitive inhibition by L-phenylalanine and the evolutionary history of the alkaline phosphatases.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Clinical and biological significance of an isozyme tumor marker--PLAP. 332 92

There are at least three alkaline phosphatase (AP) isoenzymes in man: a heat-stable placental enzyme (PLAP), a less heat-stable intestinal form (IAP), and the very heat-labile AP enriched in liver, bone and kidney. In addition to these enzymes, there is a heat-stable activity in the thymus and testis that is similar but not identical to the PLAP (the PLAP-like enzyme). Previous work has demonstrated a close structural relatedness among the IAP, PLAP and PLAP-like enzymes. Thus, it is possible that there are three human genes encoding heat-stable AP enzymes. To test this hypothesis, we have used a PLAP cDNA clone to screen a human genomic library cloned into the phage vector lambda EMBL-3. Three sets of clones were isolated, each bearing a distinct coding region homologous to the PLAP cDNA probe. Nucleotide sequence analysis of the 5' ends of these genes allowed comparison of their derived peptide sequences and positive identification of two of the genes. One of the genes encodes the PLAP (the PLAP-1 gene), another encodes the IAP, and a third closely resembles the PLAP-1 gene, but is distinct from it (the PLAP-2 gene). The PLAP-2 gene is highly homologous (greater than 95%) with the PLAP-1 except in the first exon, where sequences encoding the hydrophobic signal peptide are nearly identical with the same region of the IAP gene. These results demonstrate the existence of a small family of PLAP-related genes which is the result of at least two duplication events during the descent of man.
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PMID:Two gene duplication events in the evolution of the human heat-stable alkaline phosphatases. 344 2

The complete amino acid sequence of the precursor and mature forms of human placental alkaline phosphatase have been inferred from analysis of a cDNA. A near full-length PLAP cDNA (2.8 kilobases) was identified upon screening a bacteriophage lambda gt11 placental cDNA library with antibodies against CNBr fragments of the enzyme. The precursor protein (535 amino acids) displays, after the start codon for translation, a hydrophobic signal peptide of 21 amino acids before the amino-terminal sequence of mature placental alkaline phosphatase. The mature protein is 513 amino acids long. The active site serine has been identified at position 92, as well as two putative glycosylation sites at Asn122 and Asn249 and a highly hydrophobic membrane anchoring domain at the carboxyl terminus of the protein. Significant homology exists between placental alkaline phosphatase and Escherichia coli alkaline phosphatase. Placental alkaline phosphatase is the first eukaryotic alkaline phosphatase to be cloned and sequenced.
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PMID:Molecular cloning and sequence analysis of human placental alkaline phosphatase. 351 48


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