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)

We have constructed genes expressing single-chain antigen binding proteins (scFv) which recognize the human erbB-2 receptor. These genes encode the heavy and light chain variable domains of an erbB-2 receptor specific monoclonal antibody, MAb FRP5, connected by a peptide linker. In order to express a bifunctional molecule, a bacterial alkaline phosphatase gene was fused 3' to the scFv gene. The scFv(FRP5) and scFv(FRP5)-alkaline phosphatase fusion protein (scFv(FRP5)-PhoA) expressed in E. coli specifically recognize the human erbB-2 protein and compete with MAb FRP5 for binding to the receptor. The bound scFv(FRP5)-PhoA protein can be detected directly on tumor cells using a substrate for alkaline phosphatase, showing that the chimeric protein retains both binding and enzymatic activity.
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PMID:Construction, bacterial expression and characterization of a bifunctional single-chain antibody-phosphatase fusion protein targeted to the human erbB-2 receptor. 136 87

An alpha-neo-endorphin (alpha NE) gene, which we previously synthesized chemically and inserted into E. coli beta-galactosidase gene of pK013 plasmid, has been excised and fused to E. coli alkaline phosphatase (APase) gene. One of the transformants was named E15/pA alpha NE1. Under the APase gene regulation, APase-alpha NE chimeric protein was expressed at 1.3 X 10(6) molecules per cell, and accounted for about 60% of total cellular proteins. The HPLC pattern of CNBr treated E15/pA alpha NE1 was very simple reflecting the high content of the chimeric protein and low numbers of methionine residues in it. A series of genes encoding APase-alpha NE chimeric proteins in which 30 to 94 C-terminal amino acid residues were replaced by (met)-alpha NE, was cloned in E. coli. Transportation of the chimeric proteins to periplasmic space was studied. All chimeric proteins were apparently processed by signal peptidase but few, if any, was transported to the periplasmic space.
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PMID:Expression of chemically synthesized alpha-neo-endorphin gene fused to E. coli alkaline phosphatase. 629 40

Placental alkaline phosphatase (PLAP) is initially synthesized as a precursor (proPLAP) with a C-terminal extension. We constructed a recombinant cDNA which encodes a chimeric protein (alpha GL-PLAP) comprising rat alpha 2u-globulin (alpha GL) and the C-terminal extension of PLAP. Two molecular species (25 kDa and 22 kDa) were expressed in the COS-1 cell transfected with the cDNA for alpha GL-PLAP. Only the 22 kDa form was labelled with both [3H]stearic acid and [3H]ethanolamine. Upon digestion with phosphatidylinositol-specific phospholipase C the 22 kDa form was released into the medium, indicating that this form is anchored on the cell surface via glycosylphosphatidylinositol (GPI). A specific IgG raised against a C-terminal nonapeptide of proPLAP precipitated the 25 kDa form but not the 22 kDa form, suggesting that the 25 kDa form is a precursor retaining the C-terminal propeptide. When a mutant alpha GL-PLAP, in which the aspartic acid residue is replaced with tryptophan at a putative cleavage/attachment site, was expressed in COS-1 cells, the 25 kDa precursor was the only form found inside the cell and retained in the endoplasmic reticulum, as judged by immunofluorescence microscopy. In vitro translation programmed with mRNAs coding for the wild-type and mutant forms of alpha GL-PLAP demonstrated that the C-terminal propeptide was cleaved from the wild-type chimeric protein, but not from the mutant one. This gave rise to the 22 kDa form attached with a GPI anchor, suggesting that GPI is covalently linked to the aspartic acid residue (Asp159) of alpha GL-PLAP. Taken together, these results indicate that the C-terminal propeptide of PLAP functions as a signal to render alpha GL a GPI-linked membrane protein in vitro and in vivo in cultured cells, and that the chimeric protein constructed in this study may be useful for elucidating the mechanism underlying the cleavage of the propeptide and attachment of GPI, which occur in the endoplasmic reticulum.
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PMID:Conversion of secretory proteins into membrane proteins by fusing with a glycosylphosphatidylinositol anchor signal of alkaline phosphatase. 751 12

The signal sequence of the murine serine protease inhibitor PAI-2 promotes alkaline phosphatase export to the E. coli periplasm. However, high level expression of this chimeric protein interferes with cell growth. Since most suppressors of this toxic phenotype map to secA and secY, growth arrest results from a defective interaction of the chimeric protein with the export machinery. We have characterized suppressors which map in secG, a newly defined gene of the export machinery. All single amino acid substitutions map to three adjacent codons. These secG mutants have a weak Sec phenotype, as determined by their effect on export mediated by wild-type and mutant signal sequences. Whilst a secG disruption allele also confers a weak Sec phenotype, it does not suppress the toxicity of the chimeric protein. This difference results from a selective effect of the secG suppressors on the kinetics of export mediated by the PAI-2 signal sequence. Using a malE signal sequence mutant, which has a Mal-phenotype in secG mutant strains, we have isolated extragenic Mal+ suppressors. Most suppressors map to secY, and several are allele-specific. Finally, SecG overexpression accelerates the kinetics of protein export, suggesting that there are two types of functional translocation complexes: with or without SecG.
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PMID:A new genetic selection identifies essential residues in SecG, a component of the Escherichia coli protein export machinery. 755 84

We have designed a vector which allows the synthesis in Escherichia coli of bifunctional F(ab)2-alkaline phosphatase conjugates. The vector contains a di-cistronic operon encoding truncated heavy chain (Fd or VH-CH1) of an IgG inserted between residues +6 and +7 of bacterial alkaline phosphatase (PhoA), and the light chain of the same IgG. We demonstrate the utility of this approach with the heavy and light chain domains of a snake toxin-specific monoclonal antibody, M alpha 2-3. We show that the VH-CH1-PhoA hybrid and VL-CL are concomitantly expressed and exported to the periplasm of E. coli where they form a disulfide-linked chimeric protein. The hybrid has the same affinity as M alpha 2-3 for the snake toxin antigen and possesses PhoA enzymatic activity.
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PMID:Recombinant colorimetric antibodies: construction and characterization of a bifunctional F(ab)2/alkaline phosphatase conjugate produced in Escherichia coli. 776 7

Microsomal-type cytochrome P450s are integral membrane proteins bound to the membrane through their N-terminal transmembrane hydrophobic segment, the signal anchor sequence. To elucidate the determinants that enable the P450s to be located in the ER, we constructed cDNAs encoding chimeric proteins in which a secretory form of carboxyesterase, carboxyesterase Sec, was connected to the N-terminus of the full-length or truncated forms of a microsomal-type P450, P450(M1), and the constructed plasmids were expressed in COS cells. Since carboxyesterase Sec is an N-glycosylated secretory protein, endo H treatment could be used to determine whether these chimeric proteins were located in the ER or not. Carboxyesterase Sec with the N-terminal 20 amino acids, containing the transmembrane region, of P450(M1), was located in the ER, as determined from the endo H sensitivity of the expressed protein and immunofluorescence staining of the cells. As the expressed protein exhibited carboxyesterase activity, it was not retained in the ER through the BiP-dependent quality control system recognizing unfolded proteins. Another chimeric protein construct in which carboxyesterase Sec was connected to the C-terminal region of rat UDP-glucuronosyltransferase (UDP-GT), that contained a double-lysin ER retention motif, was also located in the ER, as determined from the endo H sensitivity and immunofluorescence staining. On the other hand, the sugar moiety of the carboxyesterase Sec connected to the transmembrane segment of UDP-GT, Sec/GTd, was partially resistant to the endo H treatment. From the results of immunofluorescent staining and cell fractionation, it was concluded that the Sec/GTd product was located in the Golgi apparatus. These observations indicated that the N-terminal hydrophobic segment of P450(M1) is sufficient for the ER membrane retention, whereas the transmembrane segment of UDP-GT is not. To determine whether microsomal P450s are recycled between the ER and Golgi compartments or not, a DNA construct encoding cathepsin D connected to the N-terminus of P450(M1) was prepared and expressed in COS cells. The fusion protein was phosphorylated, but the phosphorylation was sensitive to alkaline phosphatase. As a control, authentic cathepsin D was subjected to phosphorylation of its oligosaccharide chain that was resistant to the alkaline phosphatase treatment. Since GlcNAc-P-transferase, which forms the alkaline phosphatase-resistant phosphodiester in the sugar chains of lysosome-targeting proteins, is located in the Golgi apparatus, it was concluded that the oligosaccharide chain of the cathepsin D portion of the fusion protein was not phosphorylated, and that the chimeric protein did not go to the Golgi apparatus.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The transmembrane region of microsomal cytochrome P450 identified as the endoplasmic reticulum retention signal. 779 74

A competitive enzyme immunoassay for rat prolactin using an immunogen and a tracer obtained by recombinant DNA technology is described. Polyclonal antibodies were raised in rabbits immunized with a purified chimeric protein consisting of rat prolactin fused with two synthetic immunoglobulin G binding domains derived from staphylococcal Protein A. The enzymatic tracer was obtained using an expression system which permits insertion of rPRL DNA sequence in the alkaline phosphatase gene. Antibodies and tracer were used to develop a solid-phase competitive immunoassay for the measurement of rat prolactin in plasma with a minimal detectable concentration of 0.5 ng/ml. The mean intra- and inter-assay coefficients of variation were 7.8 and 13.2%, respectively. Rat plasma concentrations measured with this assay correlated well with those obtained with a conventional enzyme immunoassay (r = 0.993, slope = 1.037, n = 24).
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PMID:Recombinant technology in the preparation of immunogen and enzymatic tracer. Application to the development of an enzyme immunoassay for rat prolactin. 813 80

A chimera between gene segments of Protein A and a mutated alkaline phosphatase (lysine328 mutated to alanine) of Escherichia coli has been constructed. This chimeric gene was cloned in a T7 promoter-based IPTG-inducible expression vector. The chimeric protein was expressed in E. coli and was efficiently secreted into the periplasm, from which it could be easily purified by a combination of ion-exchange and gel permeation chromatography. The purified chimera was found to be thermostable and exhibited both IgG binding and high alkaline phosphatase activity. It was used as a probe in enzyme-linked immunosorbent assays and results indicate that it is a promising substitute for secondary antibodies in enzyme-linked immunoassays.
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PMID:An expression system for secretion and purification of a genetically engineered thermostable chimera of protein A and alkaline phosphatase. 816 79

IL2-PE40 is a chimeric protein composed of human interleukin 2 (IL2) genetically fused to the amino terminus of a truncated form of pseudomonas exotoxin lacking its cell recognition domain (PE40). IL2-PE40 is extremely cytotoxic to IL2 receptor positive cells. This chimeric protein was found to be an effective and selective immunosuppressive agent for IL2 receptor targeted therapy in many models of disorders of the immune response where activated T-cells play a crucial role. In an attempt to produce an improved IL2-PE40 chimeric protein, we constructed new IL2-PE derivatives. This was done by inserting defined DNA sequences within the chimeric gene encoding IL2-PE40. Inserted sequences represent motifs of other proteins known to be targeted and/or sorted to specific compartments inside or outside the cell. One of the proteins, IL2-PE40(LAP+DUP), containing a targeted signal for lysosomal membrane, was 2-3-fold more active than IL2-PE40. The insertion of the LAP sequence also increased the cytotoxicity of another IL2-PE derivative, IL2-PE664Glu. Our results suggest that a selective targeting of IL2-PE chimeric proteins to lysosomes may enable the proteins to reach the cytosol more efficiently, thus improving its specific cytotoxicity. The LAP (lysosomal alkaline phosphatase) sequence may be used as a common motif for increasing the cytotoxicity of other chimeric proteins to be used for targeted immunotherapy.
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PMID:Increased cytotoxicity of interleukin 2-pseudomonas exotoxin (IL2-PE) chimeric proteins containing a targeting signal for lysosomal membranes. 819 38

Part of the porcine rotavirus outer capsid protein VP7 containing all the three antigenic regions was expressed as a chimeric protein with bacterial alkaline phosphatase (AP) in E. coli. The construct contains an ompF promoter, the DNA encoding the signal sequence and the first 12 amino acids of mature OmpF, part of vp7 and the DNA encoding mature AP. The chimeric protein is stable, retains the biological property of AP and ability to react with polyclonal antiserum against the virus, and can be exported through the bacterial inner membrane into the periplasm.
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PMID:Periplasmic expression of part of the major rotavirus capsid protein VP7 containing all the three antigenic regions in Escherichia coli. 892 61


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