Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q07644 (polypeptide)
 72,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The phosphorescence properties of Trp109 in alkaline phosphatase from Escherichia coli have been utilized to probe the conformation of the polypeptide following the removal of metal ions, reconstitution with Zn2+ and Cd2+ and phosphorylation. The complete removal of metal ions induces a drastic loosening of the protein structure that extends to the inner core of the macromolecule. While binding of a single metal ion/subunit (A-site occupancy) restores the holoconformer, practically no structuring effect is observed upon B-site occupancy by the second incoming metal ion. An exception to this rule occurs at alkaline pH and when the adjacent subunit in the dimer is metal-free. Under these circumstances a conformation of the subunit more compact than that of the fully saturated dimer manifests some degree of communication across the subunit interface. The binding of more than two metal ions/monomer generally destabilizes the protein, the effect being more pronounced at acid pH. Finally, the binding of inorganic phosphate restores the native-like configuration abolishing any destabilization induced by excess metal ions and acid pH. If the negative cooperativity towards metal binding to A sites in doubly metalated forms at pH 8 is in substantial agreement with 113Cd-NMR data, the equivalence in conformation between Zn2+- and Cd2+-reconstituted alkaline phosphatase emphasizes that no serious structural changes are introduced by the metal replacement.
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PMID:Tryptophan phosphorescence as a monitor of the structural role of metal ions in alkaline phosphatase. 268 89

Transforming growth factors (TGF-beta 1 and TGF-beta 2) are polypeptide growth factors with a wide range of effects on the growth and differentiated function of a variety of cell types. Transforming growth factors of the beta class (TGF-beta) are found in large quantities in bone matrix and are synthesized by osteoblasts. For these reasons, it has been suggested that TGF-beta may play a major role in the regulation of bone cell metabolism. We have studied the effects of porcine TGF-beta 1 and the recently described porcine TGF-beta 2 in a mouse clonal, osteoblastlike cell line MC3T3-E1 that has previously been shown to have many characteristics of osteoblasts. In serum-containing medium, TGF-beta 1 inhibited alkaline phosphatase activity. The inhibition of alkaline phosphatase activity persisted for at least 72 h following a brief (24 h) exposure to TGF-beta 1. TGF-beta 1 also caused a marked change in cell morphology. High doses inhibited collagen synthesis; lower concentrations caused a small increase. Under serum-free conditions, TGF-beta 1 had biphasic effects on alkaline phosphatase activity inhibiting at high but stimulating at low concentrations and had only a slight stimulatory effect on collagen synthesis. Under the experimental conditions used, the effects of TGF-beta 1 on alkaline phosphatase activity and collagen synthesis were independent of effects on cell proliferation. In serum-containing medium, TGF-beta 2 inhibited alkaline phosphatase activity, an effect that was independent of changes in cell proliferation and caused shape changes in an identical fashion to that observed with TGF-beta 1.
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PMID:Effects of transforming growth factors beta 1 and beta 2 on a mouse clonal, osteoblastlike cell line MC3T3-E1. 271 77

The larval midgut epithelial cell of the silkworm, Bombyx mori, has two forms of alkaline phosphatase and trehalase, soluble and membrane-bound. Alkaline phosphatase and trehalase of the latter form are found in the brush border membrane and the basolateral membrane, respectively. In this work we studied the membrane anchors of these membrane-bound enzymes. Alkaline phosphatase was solubilized by phosphatidyl-inositol-specific phospholipase C, but not by papain. Conversely, trehalase was released from the membrane by papain, but not by phosphatidylinositol-specific phospholipase C. Both enzymes were solubilized in an amphiphilic form with 0.5% Triton X-100 plus 0.5% sodium deoxycholate (pH 7.0). The detergent-solubilized alkaline phosphatase and trehalase were converted to hydrophilic form on incubation with phosphatidylinositol-specific phospholipase C and papain, respectively. The effects of papain on solubilization and conversion of trehalase were completely inhibited by leupeptin. These results suggest that, in the silkworm larvae, alkaline phosphatase is anchored in the brush-border membrane via a glycosyl-phosphatidylinositol, while trehalase is associated with the basolateral membrane through a hydrophobic segment of the polypeptide.
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PMID:Membrane anchors of alkaline phosphatase and trehalase associated with the plasma membrane of larval midgut epithelial cells of the silkworm, Bombyx mori. 276 26

Transforming growth factor beta (TGF-beta) regulates cell growth and differentiation. Since it is abundant in bone, we have studied the effect of the polypeptide upon the growth and phenotypic expression of murine osteoblastic cells in monolayer culture. Its actions were compared to those of epidermal growth factor (EGF), another hormonally active polypeptide known to alter bone cell function. Picogram amounts of TGF-beta were found to inhibit the growth and phenotype (alkaline phosphatase and cAMP response to parathyroid hormone) of the clonal nontransformed MC3T3-E1 osteoblastic cell line. EGF also inhibited phenotypic expression, although at higher (nanogram) concentrations, but stimulated cell growth. The low concentration of TGF-beta required to inhibit growth and phenotype of osteoblastic cells together with its abundance in bone suggest that TGF-beta may be an important regulator of bone cell function.
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PMID:Transforming growth factor-beta reduces the phenotypic expression of osteoblastic MC3T3-E1 cells in monolayer culture. 283 96

Several unknown Escherichia coli genes for different species of acid phosphatase were cloned in vivo with the plasmid Mu dII4042. When present in a multicopy state, each gene promoted hydrolysis of p-nitrophenyl-phosphate at acidic pH. Among seven recombinant clones that encoded periplasmic acid phosphatase activities, five different genes could be distinguished by the pH optimum and substrate preference for the enzyme and by the restriction enzyme pattern. A 1.7-kilobase recombinant DNA fragment, common to two clones, was inserted into plasmid pBR322 and shown to contain a new gene, agp, which leads to the overexpression of the periplasmic acid glucose-1-phosphatase, a dimer of a 44-kilodalton polypeptide. Fusions of agp to gene phoA deprived of its own signal sequence conferred an alkaline phosphatase-positive phenotype to bacteria, showing the presence of an export signal on agp. The resulting hybrid proteins were characterized by immunoprecipitation with an antiserum directed against purified acid phosphatase or against alkaline phosphatase, showing that agp is the structural gene of the acid phosphatase. The beginning, the orientation, and the end of gene agp on the cloned DNA fragment were determined by the characteristics of such hybrid proteins.
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PMID:Acid phosphatases of Escherichia coli: molecular cloning and analysis of agp, the structural gene for a periplasmic acid glucose phosphatase. 284 29

A cell line, HuH-28, was established in vitro from a patient with cholangiocellular carcinoma (CCC). This cell line has grown slowly, revealing a doubling time of approximately 80 h, and the serial passages were carried out 20 times within 10 months. Light microscopy revealed spindle and polygonal morphology of the cells. Chromosome number of the cells were distributed near the hypotriploid region at passages 3 and 14. HuH-28 cells were not transplantable into nude mice, but secreted some tumor markers including alkaline phosphatase (ALP), gamma glutamyltranspeptidase (GGT), beta 2-microglobulin (BMG), ferritin, elastase-1, and tissue polypeptide antigen (TPA). This HuH-28 cell line will represent a good model for the investigation of carcinogenesis, histogenes, and diagnosis of CCC.
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PMID:Establishment and characterization of a cell line from a human cholangiocellular carcinoma. 285 88

A cell line, HuH-28 was established in vitro from a patient with cholangiocellular carcinoma (CCC). This cell line has been in continuous culture over 10 month period with slow growth potential. HuH-28 was composed of spindle-shaped cells as major population besides a small percentage of polygonal-shaped cells. Chromosome number of the cells were distributed near the hypotriploid region on the 3rd passage. HuH-28 cells were not transplantable into nude mice, but secreted some tumor markers including alkaline phosphatase (ALP), gamma glutamyltranspeptidase (GGT), beta 2-microglobulin (BMG), ferritin, elastase-1 and tissue polypeptide antigen (TPA). This HuH-28 cell line will represent a good model for the investigation of carcinogenesis, histogenesis+ and diagnosis of CCC.
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PMID:[Establishment and characterization of a human cholangiocellular carcinoma cell line]. 285 43

H+-translocating, Mg2+-ATPase was solubilized from vacuolar membranes of Saccharomyces cerevisiae with the zwitterionic detergent N-tetradecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate and purified by glycerol density gradient centrifugation. Partially purified vacuolar membrane H+-ATPase, which had a specific activity of 18 units/mg of protein, was separated almost completely from acid phosphatase and alkaline phosphatase. The purified enzyme required phospholipids for maximal activity and hydrolyzed ATP, GTP, UTP, and CTP, with this order of preference. Its Km value for Mg2+-ATP was determined to be 0.21 mM and its optimal pH was 6.9. ADP inhibited the enzyme activity competitively, with a Ki value of 0.31 mM. The activity of purified ATPase was strongly inhibited by N,N'-dicyclohexylcarbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, tributyltin, 7-chloro-4-nitrobenzoxazole, diethylstilbestrol, and quercetin, but was not affected by oligomycin, sodium azide, sodium vanadate, or miconazole. It was not inhibited at all by antiserum against mitochondrial F1-ATPase or mitochondrial F1-ATPase inhibitor protein. These results indicated that vacuolar membrane H+-ATPase is different from either yeast plasma membrane H+-ATPase or mitochondrial F1-ATPase. The vacuolar membrane H+-ATPase was found to be composed of two major polypeptides a and b of Mr = 89,000 and 64,000, respectively, and a N,N'-dicyclohexylcarbodiimide binding polypeptide c of Mr = 19,500, whose polypeptide composition was also different from those of either plasma membrane H+-ATPase or mitochondrial F1-ATPase of S. cerevisiae.
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PMID:Purification and properties of H+-translocating, Mg2+-adenosine triphosphatase from vacuolar membranes of Saccharomyces cerevisiae. 285 69

Rat liver alkaline phosphatase (ALP) was markedly induced by treatment of rats by bile-duct ligation and colchicine injection. Taking this advantage for enrichment of ALP mRNA, we constructed a lambda gt11 liver cDNA library using polyadenylated RNA prepared from the treated rat liver, and isolated an ALP cDNA clone. The 2165 bp cDNA contained an open reading frame that encodes a 524-amino-acid-residue polypeptide with a predicted molecular mass of 57737 Da. The precursor protein contained a presumed signal peptide of 17 amino acid residues followed by 28 amino acid residues identical with the N-terminal sequence determined from the purified rat liver ALP. It was also confirmed that amino acid sequences of two CNBr-cleavage peptides obtained from liver ALP were contained within the cDNA-encoded protein. Five possible N-linked glycosylation sites were found in the molecule and a highly hydrophobic amino acid sequence at the C-terminus. The deduced polypeptide of rat liver ALP showed 88% homology to that of the human liver-type enzyme in osteosarcoma cells. RNA blot hybridization analysis identified a single species of ALP mRNA with 2.7 kb in both the control and the treated rat livers. An approx. 20-fold increase of the mRNA was detected in the treated liver at 12 h after the onset of stimulation, compared with that in the control liver.
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PMID:Primary structure of rat liver alkaline phosphatase deduced from its cDNA. 289 32

Native, cell-surface insulin receptor consists of two glycoprotein subunit types with apparent masses of about 125,000 daltons (alpha subunit) and 90,000 daltons (beta subunit). The alpha and beta subunits are derived from a single polypeptide precursor by one or more proteolytic cleavages. The predominant subunit configuration in the native insulin receptor is a disulfide-linked heterotetrameric structure containing two alpha and two beta subunits. The alpha and beta insulin-receptor subunits seem to have distinct functions such that alpha appears to bind hormone whereas beta appears to possess intrinsic tyrosine kinase activity. In detergent extracts, insulin activates receptor autophosphorylation of tyrosine residues on its beta subunit, whereas in the presence of reductant, the alpha subunit is also phosphorylated. Other physiologically relevant substrates of the insulin receptor tyrosine kinase in target cells, if any, have not yet been identified. In intact cells, insulin activates serine/threonine phosphorylation of insulin receptor beta subunit as well as tyrosine phosphorylation. The biological role of the receptor-associated tyrosine kinase is not known. Tyrosine phosphorylation, catalyzed by either autophosphorylation or purified src kinase, of insulin receptor beta subunit in vitro activates the receptor kinase activity, whereas dephosphorylation with alkaline phosphatase deactivates the receptor kinase. The insulin receptor kinase is regulated by beta-adrenergic agonists and other agents that elevate cAMP in adipocytes, presumably via the cAMP-dependent protein kinase. Such agents decrease receptor affinity for insulin and partially uncouple receptor tyrosine kinase activity from activation by insulin. These effects appear to contribute to the biological antagonism between insulin and beta-agonists. The insulin receptor kinase is also inhibited in intact cells by phorbol esters that mediate serine/threonine phosphorylation of the insulin receptor, presumably via the Ca++-phospholipid-dependent protein kinase. These data suggest the hypothesis that a complex network of tyrosine and serine/threonine phosphorylations on the insulin receptor modulate its binding and kinase activities in an antagonistic manner.
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PMID:The nature and regulation of the insulin receptor: structure and function. 298 34


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