Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.1 (protein kinase)
 81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two protein kinase activities were fractionated from purified virions of avian myeloblastosis virus. Distinguishing characteristics of these two protein kinases included: (i) their binding properties during purification by ion-exchange chromatography; (ii) their estimated molecular weights; and (iii) their phosphoacceptor protein specificities. The protein kinase that bound to the anion exchanger DEAE-cellulose (pH 7.2) had an estimated molecular weight of 60,000 to 64,000 and preferred basic phosphoacceptor proteins. The protein kinase that bound to the cation exchanger phosphocellulose (pH 7.2) had an estimated molecular weight of 42,000 to 46,000 and preferred acidic phosphoacceptor proteins. The protein kinase preferring basic phosphoacceptor proteins was further purified and characterized. Optimal transfer of phosphate catalyzed by this enzyme required a divalent metal ion, a sulfhydryl-reducing agent, and ATP as phosphate donor. GTP was not an effective phosphate donor at concentrations comparable to ATP; and the cyclic nucleotides cyclic AMP and cyclic GMP neither stimulated nor inhibited protein phosphorylation by the protein kinase. The specificity of the protein kinase for basic phosphoacceptor proteins extended to proteins from avian myeloblastosis virus, in that the neutral to basic virion proteins p12, p19, and p27 served as phosphate acceptors. In addition, the protein kinase also appeared to phosphorylate itself. The role(s) of this virion-associated protein kinase is discussed.
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PMID:Fractionation of two protein kinases from avian myeloblastosis virus and characterization of the protein kinase activity preferring basic phosphoacceptor proteins. 22 78

p19 is a highly conserved 19-kDa cytosolic protein that undergoes phosphorylation in mammalian cells upon activation of several distinct signal transduction pathways. Its expression is widespread but developmentally regulated. To determine the in vivo phosphorylation site(s) of p19, the protein was purified from bovine brain and resolved into the unphosphorylated form (p19) and a mixture of the two predominant phospho-forms (pp19). Proteolytic fragments of p19 and pp19 were examined by liquid chromatography/mass spectrometry (LC/MS). We detected ion masses corresponding to fragments spanning the entire amino acid sequence as deduced from the cDNA except for those predicted to contain an unmodified amino terminus. Instead, the digests revealed ions corresponding to peptides lacking the initiator methionine and containing an N-acetylated alanine at the amino terminus. The analysis of pp19, but not that of p19, revealed two sets of ions representing peptides whose m/z values differed by 80 atomic mass units, the incremental mass of a phosphate residue. These putative phosphate-bearing peptides were sensitive to alkaline phosphatase treatment. Using combined trypsin and V8 protease digestions, the phosphorylation sites were mapped to Ser-25 and Ser-38, in the peptides Leu-Ile-Leu-Ser*-Pro-Arg and Phe-Pro-Leu-Ser*-Pro-Pro-Lys, respectively. Interestingly, both phosphoserines are in a very similar sequence context, suggesting that a single proline-directed serine protein kinase, possibly p34cdc2, is responsible for phosphorylation of both sites in vivo.
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PMID:Analysis of phosphoprotein p19 by liquid chromatography/mass spectrometry. Identification of two proline-directed serine phosphorylation sites and a blocked amino terminus. 173 1

The expression of phosphoprotein p19, a 19-kDa cytosolic substrate for cyclic adenosine monophosphate (cAMP)-dependent protein kinase, occurs abundantly in brain and testis and is developmentally regulated. In the present study we have identified the cell types of adult rat testis that contain p19. Using cryostat sections, which were first incubated with rabbit anti-p19 for immunohistochemistry followed by counterstaining with periodic acid-Schiff (PAS)-hematoxylin to reveal nuclear morphology, we demonstrate that immunoreactive p19 is detectable only in germ cells and is restricted to a limited stage of spermatogenesis. Expression first appears after the differentiating gametes have entered the prophase of meiosis, is abundant in spermatocytes until meiosis is completed, and declines to undetectable levels in maturing spermatids. We have ruled out immunocross-reactivity with SCG10, a 22-kDa protein that is closely related in structure to p19, by demonstrating, using Northern blot analysis, that RNA transcripts encoding SCG10 are not detectable in adult rat testis, whereas p19 is abundantly expressed. The transient expression of p19 during spermatogenesis suggests that the protein plays a role during male gamete differentiation.
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PMID:Stage-specific expression of phosphoprotein p19 during spermatogenesis in the rat. 222 88

We have developed a one-step purification procedure for proteins containing the N-terminal portion of the gag protein of avian sarcoma and leukemia viruses. In this procedure, a resin with a covalently attached monoclonal antibody to the gag protein p19 is used to bind gag-containing proteins from crude extracts. After washing of the resin, the bound proteins are eluted with 2 M MgCl2. For the transforming protein kinase encoded by Fujinami sarcoma virus p130gag-fps, this procedure gave an enrichment of several thousand-fold, a yield of over 10%, a final purity of over 20%, and no significant loss of protein kinase activity. Similar purifications were obtained with three other gag-containing proteins. The immunoaffinity purification described may be of general utility as a first step in purification of the several other avian retroviral transforming proteins that are synthesized from fusions of an oncogene with the viral gag gene.
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PMID:A simple method for immunoaffinity purification of nondenatured avian sarcoma and leukemia virus gag-containing proteins. 282 89

To elucidate the biological mechanisms of 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced phenotypic changes in HTLV-I virus-infected human T-cell line KH-2Lo cells, inhibitors of TPA-induced ornithine decarboxylase (ODC), protein kinases and calmodulin were examined for their effects on TPA-induced multinucleated cell formation and HTLV-I p19 antigen expression. Among the inhibitors of TPA-induced ODC activity, alpha-difluoromethyl ornithine (DFMO), 1,25(OH)2D3 and its analogues, and retinoic acid were tested. As inhibitors of protein kinases, 1-(5-isoquinolinyl-sulfonyl)-2-methylpiperazine (H-7), N-[2-(methylamino)ethyl]-5-isoquinoline-sulfonamide (H-8) and 1,(5-isoquinolynylsulfonyl)-2,3-dimethylpiperazine (H-5) were used. In addition, a calmodulin inhibitor, N-(4-aminobutyl)-5-chlor-2-naphthalenesulfonamide (W13) and its inactive analogue, N-(4-aminobutyl)-2-naphthalenesulfonamide (W12) were also tested. 1,25(OH)2D3 and its active analogues inhibited both TPA-induced HTLV-I p19 antigen expression and multinucleated cell formation after 4 days of culture with TPA. On the other hand, an inhibitor of ODC, DFMO, the protein kinase inhibitors, the calmodulin inhibitor and retinoic acid suppressed TPA-induced HTLV-I p19 expression but did not suppress multinucleated cell formation.
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PMID:Inhibitors of 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced multinucleated cell formation and HTLV-I p19 antigen expression in HTLV-I-infected T-cell line KH-2Lo. 301 86

The structural proteins and the oncogene product of the avian sarcoma virus (ASV) D6 were analyzed by the radioimmunoprecipitation. ADV D6 was obtained from the chemically induced tumour. ASV D6 contains all the structural proteins found in RSV, but some of them (p19, gp 85) differ from those of RSV. The product of ASV D6 oncogene is pp65src. The protein kinase activity of this src protein is identical to that of wt pp60src. The nature of some other proteins, which can be phosphorylated in this reaction, is discussed.
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PMID:[Virus-specific proteins in cells transformed by the chicken sarcoma virus D6]. 301 82

The 28,000 mol. wt. polypeptide (p28) of adult T-cell leukaemia-associated antigen encoded by the 24S defective human T-cell leukaemia virus (HTLV-I) is associated with protein kinase activity. We have determined the nucleotide sequence of this defective HTLV-I provirus and found that it contains a portion of the gag gene (p19 and part of p24), the pX region, and two long terminal repeats, one at each end. The predicted p28 gag-pX fused protein consists of 190 amino acids and its mol. wt. was calculated as 21,055. The results of peptide mapping analysis showing that p28 contains p19 supported the nucleotide sequence data. That p28 was encoded by this defective provirus was also demonstrated by transient expression of p28 polypeptide in COS 7 cells transfected with a recombinant plasmid containing a simian virus 40 early promoter and the p28-coding region of the 24S HTLV-I.
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PMID:Structural analysis of p28 adult T-cell leukaemia-associated antigen. 301 50

We report the purification from bovine brain and describe some of the properties of a 19-kDa protein, p19, which we have previously shown to undergo hormone-dependent, cAMP-mediated phosphorylation in several peptide hormone-producing tumor cells. The procedure for purifying p19 to apparent homogeneity utilized ammonium sulfate fractionation, sequential chromatography on DEAE-cellulose and phenyl-Sepharose, followed by fast protein liquid chromatography using a Mono Q and, finally, a C8 reverse-phase column. The yield was 0.3-0.5 mg of p19/kg of brain. The molecular weight (Mr = 19,000) and frictional ratio (f/f0 = 1.87) of p19, which were derived from its Stokes radius (33 A) and sedimentation constant (s20,w = 1.4), suggest that the native form of p19 is an asymmetrically shaped monomer. We provide evidence to suggest that p19 is isolated as a mixture of molecular forms consisting of an unphosphorylated form and of three phosphoforms indicative of multisite phosphorylation. These forms cosedimented on sucrose density gradients and coeluted on gel filtration, hydrophobic chromatography, and reverse-phase fast protein liquid chromatography. They were resolved from each other by anion-exchange chromatography. The unphosphorylated form (pI 6.2) was phosphorylated by catalytic subunit of cAMP-dependent protein kinase to a stoichiometry of 0.5 mol of P/mol of p19, thereby giving rise to the three phosphoforms (pI 5.8, pI 5.6, and pI 5.2, respectively). We conclude that p19 is a novel cAMP-dependent protein kinase substrate protein that is present in brain and in peptide hormone-producing tumor cells. Its function remains to be identified.
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PMID:Properties of p19, a novel cAMP-dependent protein kinase substrate protein purified from bovine brain. 362 37

The nucleotide sequence of a PstI fragment prepared from a cloned MH2 virus genome, pMH2-Hd, has been deduced using chemical and enzymatic methods. This fragment, 1862 nucleotides in length, starts with the gag gene, encodes the v-mil sequence and stops within the v-myc gene. This sequence shows that the v-mil gene is fused to the gag gene giving rise to a fused polyprotein of 98 000 daltons: 515 amino acids at the amino terminus would correspond to p10, p19, p27 and part of p12 determinants, 347 amino acids at the carboxy terminus correspond to the v-mil specific sequence. The mil protein shares homology with a number of onc proteins such as src, fes, fms, mos, yes, fps and erbB, as well as with the catalytic chain of the cAMP-dependent protein kinase. This PstI fragment also encodes the beginning of the myc gene which was integrated in MH2 along with the 3' end of the preceding intron placing an acceptor splice site in front of the used open reading frame. As deduced from the sequence, the MH2 myc protein is not identical to the MC29 myc protein. It differs at its amino terminus, which contains little or no gag determinants, depending on the ATG used to initiate translation.
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PMID:The second oncogene mil of avian retrovirus MH2 is related to the src gene family. 608 17

The biological and biochemical properties of the transformation-specific proteins of three avian oncornaviruses with different oncogenic potentials were compared, namely the gag-myc protein of the avian myelocytomatosis virus MC29, the gag-erb A protein of the avian erythroblastosis virus AEV, and the gag-fps protein of Fujinami sarcoma virus FSV. These oncogenes were analyzed in transformed fibroblasts that expressed only the transforming proteins but showed no virus replication. Monoclonal antibodies against the viral structural protein p19, which is the N-terminus of the proteins, were used for indirect immunofluorescence, for immunoprecipitation of the proteins from subcellular fractions, and for immunoaffinity column chromatography. With this last method a 3000-fold purification of the proteins was obtained. By indirect immunofluorescence it was shown that the gag-myc protein was located in the nucleus, and bound to DNA after purification. The gag-erb A protein was not nuclear but probably located in the cytoplasm and did not bind to DNA after purification. Neither of the two proteins exhibited protein kinase activity. In contrast, the gag-fps protein did not bind to DNA but showed protein kinase activity after purification. It was not located in the nucleus either.
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PMID:Biochemical characterization of transformation-specific proteins of acute avian leukemia and sarcoma viruses. 629 58


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