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)

The protozoan parasite Leishmania mexicana secretes a heavily glycosylated 100-kDa acid phosphatase (sAP) which is associated with one or more polydisperse proteophosphoglycans. Most of the glycans in this complex were released using mild acid hydrolysis conditions that preferentially cleave phosphodiester linkages. The released saccharides were shown to consist of monomeric mannose and a series of neutral and phosphorylated glycans by Dionex high performance liquid chromatography, methylation analysis, exoglycosidase digestions, and one-dimensional 1H NMR spectroscopy. The neutral species comprised a linear series of oligosaccharides with the structures [Man alpha 1-2]1-5Man. The phosphorylated oligosaccharides were characterized as PO4-6Gal beta 1-4Man and PO4-6[Glc beta 1-3]Gal beta 1-4Man. The attachment of these glycans to the polypeptide backbone via the linkage, Man alpha 1-PO4-Ser, is suggested by: 1) the finding that more than 60% of the serine residues in the polypeptide are phosphorylated and 2) the resistance of the phosphoserine residues to alkaline phosphatase digestion unless the sAP was first treated with either mild acid (to release all glycans) or jack bean alpha-mannosidase (to release neutral mannose glycans). Analysis of the partially resolved components of the complex indicated that the most of the O-linked glycans on the 100-kDa phosphoglycoprotein comprised mannose and the mannose-oligosaccharides. In contrast the major O-linked glycans on the proteophosphoglycan were short phosphoglycan chains, containing on average two repeat units per chain. In addition to the O-linked glycans, both components in the sAP complex contained N-linked glycans. The N-glycanase F-released glycans were characterized by Bio-Gel P4 chromatography and exoglycosidase digestions to be the biantennary oligomannose type with the structures Glc1Man6GlcNAc2 and Man6GlcNAc2. The O-linked glycans of the sAP complex are similar to those found in the phosphoglycan chains of the abundant surface lipophosphoglycan, but differ in having much shorter phosphoglycan chains and a more diverse series of mannose cap oligosaccharides. These data suggest that there are marked differences in the ability of different glycosyltransferases to utilize peptide-linked versus glycolipid-linked acceptors.
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PMID:O- and N-glycosylation of the Leishmania mexicana-secreted acid phosphatase. Characterization of a new class of phosphoserine-linked glycans. 792 59

P1 protamines isolated from ejaculated human, stallion, bull, boar and ram spermatozoa and P2 protamines from human and stallion spermatozoa were subjected, after alkaline phosphatase treatment, to in vitro phosphorylation reactions using cAMP-dependent protein kinase (PKA) and protein kinase C (PKC). All P1 protamines were phosphorylated by PKA, whereas P2 protamines were phosphorylated only by PKC. In addition, human, stallion and boar, but not bull and ram, P1 protamines were phosphorylated by PKC. After phosphoamino acid analysis, the protamines showing positive signals for phosphoserine (P-Ser) were subjected to P-Ser conversion reaction and protein sequencing. Only stallion (St1) and human (HP1) P1 protamines contained P-Ser after PKA phosphorylation, located in the middle region of the molecule, i.e., at Ser29 in St1 and Ser28 in HP1. All other phosphorylated P1 protamines contained only P-Thr, which could not be further localized in the sequence with the present methods. After PKC phosphorylation, the internally located Ser residues in human (ser21) and stallion (Ser29) P1 protamines were phosphorylated and, in boar P1 protamine, only Thr43 was slightly phosphorylated. The N-terminally located Ser residues in P1 protamines, which are known to be phosphorylated in vivo, were not phosphorylated by either kinase, indicating that there must still be other types of protamine kinases in sperm cells responsible for their phosphorylation. Within P2 protamines, HP2 was equally well phosphorylated at all Ser residues in addition to some Thr phosphorylation, whereas, in St2, Ser32 was the main target for PKC phosphorylation in vitro. Collectively, PKC is a good candidate for in vivo phosphorylation of P2 protamines and PKA for phosphorylation of some hydroxyamino acid residues in P1 protamines.
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PMID:P2 protamines are phosphorylated in vitro by protein kinase C, whereas P1 protamines prefer cAMP-dependent protein kinase. A comparative study of five mammalian species. 803 90

Epidermal growth factor (EGF) stimulated the phosphorylation of connexin43 (Cx43) in WB cells as evidenced by the formation of multiple immunoreactive Cx43 proteins of higher molecular mass which were abolished by treatment with alkaline phosphatase. Phosphorylation of Cx43 occurred within 10 min of EGF stimulation, was sustained for 1 h, and was associated with almost complete inhibition of gap junctional communication in these cells. EGF-induced phosphorylation and communication inhibition were retained in cells pretreated with phorbol 12-myristate 13-acetate (PMA) to deplete protein kinase C. These results show that the EGF inhibition of communication is tightly linked to protein kinase C-independent phosphorylation of Cx43. Further, Cx43 phosphorylated in the presence of EGF did not react with phosphotyrosine antibodies and in 32Pi incorporation experiments was shown to contain only phosphoserine indicating that the tyrosine kinase activity of the EGF receptor was not directly involved.
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PMID:Epidermal growth factor inhibits gap junctional communication and stimulates serine-phosphorylation of connexin43 in WB cells by a protein kinase C-independent mechanism. 808 76

Two forms of alkaline phosphatase exist in the integument of the "white pupae" (wp) and dark pupae (dp) mutant strains of Ceratitis capitata, during transition from larvae to pupae. They were separated by DEAE-cellulose chromatography. Both isoenzymes have a molecular weight of approximately 180,000 and two pH optima, at 9.4 and at 11.0. The isoenzymes of the "dark pupae" mutant catalyze the hydrolysis of phosphotyrosine and beta-glycerophosphate but not phosphoserine, phosphothreonine, ATP, and AMP. In contrast, the isoenzymes of the white pupae mutant hydrolyze all the substrates tested. The ALPase 1 of the dark pupae mutant was inhibited by L-tyrosine, but L-phenylalanine had no effect on either isoenzyme. The effects of divalent cations, EDTA, temperature, urea, and 2-mercaptoethanol were also investigated. Electrophoretic analysis did not reveal any variants of the larval and pupal isoenzymes, but ALPase A, an adult stage-specific isoenzyme, was found to be polymorphic. The electrophoretic variants were shown to be controlled by three codominant alleles located on the third chromosome of Ceratitis capitata. Since we found no hybrid enzyme, we conclude that ALPase A is monomeric.
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PMID:Biochemical and genetic studies on alkaline phosphatase of Ceratitis capitata. 812 97

In vivo 31P NMR has been used to characterize the phosphorylated compounds present in the heart from vertebrate ectotherms. The perfused hearts from all animals experimented showed prominent resonances between the inorganic phosphate and phosphocreatine peaks. The pattern of these compounds was found to be different in the heart of the different species. As shown by 31P and proton NMR of perchloric extracts, the chemical shift of some of the compounds was characteristic of glycerophosphorylcholine, glycerophosphorylinositol, phosphorylcholine, phosphorylserine, phosphorylethanolamine and phosphoenolpyruvate. The non-identified resonances were found to be phosphodiesters, as demonstrated by alkaline phosphatase hydrolysis. The physiological significance of these high levels of phosphodiesters in the heart from vertebrate ectotherms is discussed.
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PMID:Detection of phosphodiester resonances in the perfused heart from vertebrate ectotherms with nuclear magnetic resonance. 825 Sep 49

Recent immunohistochemical experiments revealed that specific anti-neurofilament monoclonal antibodies yield distinct patterns in different types of neurons. This led to the suggestion that neurofilaments are a family of heterogeneous molecules whose occurrence and distribution are a function of cell type. In the present study we examined the hypothesis that this heterogeneity is due to differences in the extent of phosphorylation of neurofilament proteins in distinct types of neurons. In view of the large number of potential phosphorylation sites on the heavy neurofilament protein (NF-H), we focused on this protein and examined its extent of phosphorylation in different types of neurons. This was performed using neurofilaments isolated from axons of the cholinergic bovine ventral root motor neurons and of the chemically heterogeneous bovine dorsal root neurons. Two-dimensional gel electrophoresis revealed that the isoelectric point of ventral root NF-H (pl 5.10) was approximately 0.2 pl units more acidic than that of dorsal root NH-F. This difference was abolished by treating the neurofilaments with alkaline phosphatase, suggesting that the excess negative charge of ventral root NF-H is due to increased levels of phosphorylation. Amino acid analysis confirmed that the phosphoserine content of ventral root NF-H (27.2 +/- 2.5% of the serines) is markedly higher than that of dorsal root NF-H (15.5 +/- 6.2% of the serines). These findings provide a novel system for studying the biochemistry and function of distinctly phosphorylated neurofilaments in different types of neurones.
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PMID:Distinctly phosphorylated neurofilaments in different classes of neurons. 829 39

The aim of the present study was to determine to what extent the rate at which collagen mineralizes correlates with the amount and nature of bound phosphate groups. Sheets of collagen prepared from demineralized bovine dentin or cortical bone were complexed with various concentrations of phosphoserine [(P)Ser] or rat dentin phosphoproteins (PP; lowly or highly phosphorylated PP, LPP or HPP). Alternatively, phosphate groups were removed from the collagenous carrier material by treatment with phosphatases. Mineralization was achieved by incubation in culture medium supplemented with 45Ca, alkaline phosphatase and 10 mM beta-glycerophosphate. The sheets were monitored for uptake of 45Ca and lag times calculated and plotted against the amount of bound phosphate. It was observed that dephosphorylation of the carrier causes an increase in lag time and that rat PP decreases lag times in a concentration-dependent way. HPP were more effective than LPP. (P)Ser or other small organic P-containing molecules had hardly any influence on lag time. It is concluded that next to the amount of bound phosphate, the nature of phosphorylated substances has considerable influence on the rate of mineralization of a collagenous carrier.
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PMID:Effect of bound phosphoproteins and other organic phosphates on alkaline phosphatase-induced mineralization of collagenous matrices in vitro. 830 80

Radiation inactivation technique was employed to determine the functional size of phosphatases from thylakoid membrane. The enzymatic activities of phosphatases decayed in a simple function with the increase of radiation dosage. D37 values of 18.8 +/- 2.4-14.1 +/- 1.5 Mrad were obtained, using phosphoserine, phosphothreonine, p-nitrophenol phosphate, and phospho-histone V-S, respectively, as substrates. The molecular masses of 48.2 +/- 6.3-61 +/- 5.7 kDa were yielded by target theory analysis. We thus speculate that the thylakoid alkaline phosphatase is probably a monomer while acid phosphatase is functionally a dimer in situ.
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PMID:Functional size of the thylakoid phosphatases determined by radiation inactivation. 843 18

Protein phosphatase 2A is a heterotrimeric protein serine/threonine phosphatase consisting of a 36-kDa catalytic C subunit, a 65-kDa structural A subunit, and a variable regulatory B subunit. The B subunits determine the substrate specificity of the enzyme. There have been three families of cellular B subunits identified to date: B55, B56 (B'), and PR72/130. We have now cloned five genes encoding human B56 isoforms. Polypeptides encoded by all but one splice variant (B56gamma1) are phosphoproteins, as shown by mobility shift after treatment with alkaline phosphatase and metabolic labeling with [32P]phosphate. All labeled isoforms contain solely phosphoserine. Indirect immunofluorescence microscopy demonstrates distinct patterns of intracellular targeting by different B56 isoforms. Specifically, B56alpha, B56beta, and B56epsilon complexed with the protein phosphatase 2A A and C subunits localize to the cytoplasm, whereas B56delta, B56gamma1, and B56gamma3 are concentrated in the nucleus. Two isoforms (B56beta and B56delta) are highly expressed in adult brain; here we show that mRNA for these isoforms increases severalfold when neuroblastoma cell lines are induced to differentiate by retinoic acid treatment. These studies demonstrate an increasing diversity of regulatory mechanisms to control the activity of this key intracellular protein phosphatase and suggest distinct functions for isoforms targeted to different intracellular locations.
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PMID:The B56 family of protein phosphatase 2A (PP2A) regulatory subunits encodes differentiation-induced phosphoproteins that target PP2A to both nucleus and cytoplasm. 870 17

PA28, also referred to as 11S regulator, is a potent activator of the peptidase activities of the proteasome (multicatalytic proteinase complex). Although the role(s) of PA28-20S proteasome complexes in cellular proteolytic processes remain to be defined, these particles have been implicated in antigen processing of major histocompatibility complex (MHC) class I molecules. Our results demonstrate that PA28 is phosphorylated as evidenced by 32P incorporation into a single PA28 species in rabbit reticulocytes. In reticulocytes as well as human erythrocytes, PA28 is normally found in a phosphorylated state as detected by phosphoserine antibody. In human erythrocytes, this antibody recognizes three polypeptides which are also detected by antibody to PA28 on Western blot analysis. Dephosphorylation with alkaline phosphatase treatment completely abolishes the ability of PA28 to activate hydrolysis of Suc-Leu-Leu-Val-Tyr by proteasomes. After exposure to phosphatase, the three polypeptides are no longer recognized by phosphoserine antibody, although binding to PA28 antibody is unaffected. These results suggest that phosphorylation may function in transduction of cytokine and growth factor signals that, in turn, modulate antigen presentation and other processes which involve PA28-20S proteasome complexes.
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PMID:Phosphorylation of the proteasome activator PA28 is required for proteasome activation. 878 Jul 2


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