Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In chronic granulocytic leukemia (CGL) the Philadelphia translocation results in the production of a novel 210 kDa bcr-abl fusion protein which shows increased tyrosine protein kinase activity in comparison with its normal 145 kDa c-abl counterpart. Using an immunoblotting method and antiphosphotyrosine antibody, we have identified the tyrosine protein kinase substrates present in intact cells from two Philadelphia-positive CGL derived cell lines (K562 and BV173) and compared these with the substrates present in a Philadelphia-negative myeloid cell line (HL60). We have demonstrated an increased number of substrates, particularly of low (less than 110 kDa) molecular weight in the K562 or BV173 cells compared with the HL60 cells. There is virtual identity of the substrates present in the two CGL-derived lines. This work supports the hypothesis that the functional changes present in the bcr-abl 210 kDa protein of CGL results in altered tyrosine phosphorylation of intracellular proteins and that this is of importance in the pathogenesis of CGL.
Leukemia 1987 Jun
PMID:Tyrosine protein kinase substrates in Philadelphia-positive human chronic granulocytic leukemia derived cell lines (K562 and BV173): detection by using an immunoblotting technique. 244 34

To test whether cellular protein kinases exist that phosphorylate D-amino acid residues, a method was developed for separating O-phospho-D-serine from O-phospho-L-serine and O-phospho-L-tyrosine from O-phospho-D-tyrosine. This was accomplished by converting these amino acids to the L-leucyl dipeptide derivatives followed by separation of the diastereomers by anion-exchange high-performance liquid chromatography. The enantiomeric content of these D- and L-residues were measured in hydrolysates of 32P-labeled proteins produced by the protein kinases of human erythrocytes and the tyrosyl protein kinase of the Abelson leukemia virus. We found no measurable D-phosphoserine in erythrocyte membrane proteins under conditions where a 1% content of this residue relative to L-phosphoserine would have been detected. These values can be used to place an upper hypothetical limit on the fraction of erythrocyte protein kinase activity that is specific for serine residues in the D-configuration. In separate experiments, we examined the specificity of the tyrosyl protein kinases. We found that all of the phosphotyrosine that we isolated from the erythrocyte band 3 NH2-terminal fragment and from the autophosphorylation of the Abelson virus tyrosyl kinase was in the L-configuration.
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PMID:The stereospecificity of protein kinases. 244 31

Previous studies have shown that carboxyl-terminal mutation of pp60c-src can activate its transforming ability. Conflicting results have been reported for the transforming ability of pp60c-src mutants having only mutations outside its carboxyl-terminal region. To clarify the effects of such mutations, we tested the activities of chimeric v(amino)- and c(carboxyl)-src (v/c-src) proteins at different dosages in NIH 3T3 cells. The focus-forming activity of Rous sarcoma virus long terminal repeat (LTR)-src expression plasmids was significantly reduced when the v-src 3' coding region was replaced with the corresponding c-src region. This difference was masked when the Rous sarcoma virus LTR was replaced with the Moloney murine leukemia virus LTR, which induced approximately 20-fold more protein expression, but even focus-selected lines expressing v/c-src proteins were unable to form large colonies in soft agarose or tumors in NFS mice. This suggests that pp60c-src is not equally sensitive to mutations in its different domains and that there are at least two distinguishable levels of regulation, the dominant one being associated with its carboxyl terminus. v/c-src chimeric proteins expressed with either LTR had high in vitro specific kinase activity equal to that of pp60v-src but, in contrast, were phosphorylated at both Tyr-527 and Tyr-416. Total cell protein phosphotyrosine was enhanced in cells incompletely transformed by v/c-src proteins to the same extent as in v-src-transformed cells, suggesting that the carboxyl-terminal region may affect substrate specificity in a manner that is important for transformation.
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PMID:v-src mutations outside the carboxyl-coding region are not sufficient to fully activate transformation by pp60c-src in NIH 3T3 cells. 245 Nov 22

We have deduced the sequence of the protein encoded by the chicken c-yes gene from overlapping cDNA clones. The predicted protein, p61c-yes, contains 541 amino acids and has a molecular weight of 60,911 with the amino terminal methionine residue. Chicken p61c-yes differs from Y73 virus p90gag/v-yes in three respects. First, the carboxy-terminal eight amino acids of p61c-yes are replaced by three amino acids in p90gag/v-yes, which are encoded by the avian leukemia virus env gene. This alteration changes the position and context of a tyrosine residue in p61c-yes. Second, nucleotides which are present as 5' non-translated sequence in the p61c-yes mRNA, are translated in the p90gag/v-yes mRNA. Third, there are fourteen dispersed nucleotide differences in Y73 v-yes which result in six amino differences between the body of p90gag/v-yes and p61c-yes. Chicken p61c-yes differs from human p61c-yes at 43 residues, and from chicken pp60c-src at 122 residues.
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PMID:The sequence of chicken c-yes and p61c-yes. 246 85

P210bcr/abl protein with tyrosine protein kinase has been implicated in the proliferation and differentiation of chronic myelogenous leukemia cells. Using an immunoblotting technique with antiphosphotyrosine (anti-P-Tyr) antibodies, we examined whether P210bcr/abl protein was expressed in chronic phase cells in patients with chronic myelogenous leukemia (CML). We could detect P210bcr/abl protein in blast cells regardless of myeloid or lymphoid lineage but not in chronic phase cells from patients. However, in a patient with both blast cells and chronic phase cells, we could identify the protein only after the enrichment of the blast crisis cells by Percoll gradient centrifugation. When K562 cells were mixed with mature granuloid cells, the P210bcr/abl in K562 cells detected by immunoblotting was decreased. Using phosphotyrosyl proteins in K562 cells as substrates, high phosphotyrosyl (P-Tyr) phosphatase activity was observed, not only in the lysate of chronic phase cells from CML patients but also in the lysate of neutrophils from normal subjects. These findings suggest the possibility that high P-Tyr phosphatase activity prevents the detection of P210bcr/abl in CML cells in the chronic phase. The activity may be characteristic of mature cells and may regulate cellular events through dephosphorylation of P210bcr/abl.
Leukemia 1989 Sep
PMID:Phosphotyrosine phosphatase activity prevents the detection of P210bcr/abl protein in mature cells in chronic myelogenous leukemia even by an immunoblotting technique. 247 29

The octapeptide E-E-K-E-Y-H-A-E, corresponding to the amino acid sequence 841-845 of EGF receptor, whose tyrosine-845 is homologous to the main phosphorylation site of pp60v-src, has been synthesized together with seven shorter peptides encompassing variable segments around the tyrosine residue. The peptides have been employed as model substrates for inspecting the local structural determinants of three tyrosine protein kinases (TPKs), namely; TPK-IIB and TPK-III, isolated from lymphoid cells (Eur. J. Biochem. 172, 451-457 (1988] and the TPK encoded by the oncogene of Abelson murine leukemia virus. The phosphorylation order with the different peptide substrates is variable depending on the TPK used: in particular, the lysine residue at position -2 relative to tyrosine proved especially harmful with TPK-IIB, the peptides K-E-Y-H and K-E-Y-H-A-E being very poor substrates compared with their shorter derivatives devoid of the N-terminal lysine (E-Y-H and E-Y-H-A-E, respectively). Conversely, such a basic residue is well tolerated by the other two TPKs. The negative effect of the N-terminal lysine on TPK-IIB-catalyzed phosphorylation is accounted for by an increase of Km and can be overcome by the presence of additional glutamic acid(s) on that side. On the other hand, the C-terminal acidic doublet Ala-Glu specifically impairs the phosphorylation efficiency of abl-TPK, by lowering the Vmax value, the heptapeptide E-K-E-Y-H-A-E being much less readily phosphorylated than E-K-E-Y-H. Collectively, these results would indicate that the site specificity of tyrosine protein kinases results from the balance of positive and negative determinants whose influence on the catalytic activity of the individual enzymes can differ greatly.
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PMID:Synthetic peptides reproducing the EGF-receptor segment homologous to the pp60v-src phosphoacceptor site. Phosphorylation by tyrosine protein kinases. 250 Sep 78

The avian sarcoma/leukemia virus protease (PR), purified from avian myeloblastosis virus has a native molecular mass of 26 kDa, suggesting a dimer structure. The enzymatic activity of PR has been characterized using synthetic peptide substrates. PR is most active at pH 5.5, 35 degrees C and 2-3 M NaCl. Under these conditions PR cleaves decapeptides which are resistant in low ionic strength. This high, nonphysiological, salt concentration also increases the proteolytic activity of a cellular aspartic protease, pepsin. PR and pepsin show additional similarities: they both cleave a synthetic decapeptide at the same Tyr-Pro bond in low and high salt, while the cleavage site preferences of human renin and cathepsin-D in this substrate are altered at high salt concentrations. In addition, iodination of the tyrosine residue in this decapeptide causes an increase in the rates of hydrolysis by both PR and pepsin. However, Km values are too high to be estimated accurately for PR using Tyr-Pro and Tyr(I)-Pro decapeptides as substrates. Comparison of the digestion products of two additional decapeptides, altered in a single amino acid residue, shows that PR cleaves at fewer sites than all three cellular enzymes. Furthermore pepstatin, a strong inhibitor of pepsin, renin, and cathepsin-D has little effect on PR.
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PMID:Avian retroviral protease and cellular aspartic proteases are distinguished by activities on peptide substrates. 253 48

Abelson murine leukemia virus (A-MuLV) encodes a single protein product, a tyrosine-specific protein kinase, whose activity is necessary for cell transformation by this retrovirus. Using a defined medium culture system, we demonstrate that transformation of NIH 3T3 fibroblasts by A-MuLV abrogates their normal requirement for platelet-derived growth factor (PDGF) for cell growth. Analysis of constructed insertional mutant viruses revealed an absolute correlation between A-MuLV-encoded tyrosine kinase activity and PDGF-independent fibroblast growth. Sequences of the provirus not required for kinase activity appeared unnecessary for abrogating the fibroblast requirement for PDGF. Conversely, sequences required for kinase activity appeared necessary, suggesting that induction of PDGF-independent fibroblast growth, like cell transformation, is a function of this tyrosine kinase. Fibroblasts transformed by a partially transformation-defective mutant demonstrated incomplete morphological transformation but were still independent of PDGF for growth. Thus, the processes of full morphological transformation and growth factor independence can be partially dissociated.
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PMID:Abelson murine leukemia virus induces platelet-derived growth factor-independent fibroblast growth: correlation with kinase activity and dissociation from full morphologic transformation. 253 21

Adriamycin, a lipid-interacting anti-cancer agent, was found to inhibit the phosphorylation of polyGlu/Tyr (4:1) by tyrosine protein kinases either from spleen or expressed by the oncogene of Abelson murine leukemia virus. The dose dependent inhibition by adriamycin is accounted for by competition for the ATP binding site, but it is also deeply influenced by the nature and concentration of the phosphorylatable substrate, suggesting multiple interactions with the enzyme. The phosphorylation at tyrosine residues of cytosolic proteins from cells transformed by Abelson leukemia virus and the autophosphorylation of tyrosine protein kinases are also inhibited by adriamycin. Unlike tyrosine protein kinases most serine/threonine specific protein kinases, with the notable exception of protein kinase-C, appear to be relatively insensitive to adriamycin.
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PMID:Inhibition of tyrosine protein kinases by the antineoplastic agent adriamycin. 254 96

Expression of the proto-oncogene p93c-fes and its associated tyrosine kinase activity is marked in mature granulocytes, monocytes, differentiated HL-60 leukemia cells, and leukemia cell lines KG-1, THP-1, HEL, and U-937, which can be induced to differentiate along the granulocyte/monocyte pathway. Conversely, p93-c-fes expression is absent in the K562 cell line, which is resistant to myeloid differentiation. Upon transfection and clonal selection of K562 cells using a mammalian expression vector containing the 13-kilobase pair c-fes gene, c-fes mRNA was transcribed and p93-c-fes tyrosine activity kinase was expressed. Clones expressing c-fes underwent myeloid differentiation as assessed by the appearance of phagocytic activity, Fc receptors, nitro blue tetrazolium reduction, Mac-1 immunofluorescence, and lysozyme production. These results indicate that the expression of the c-fes protooncogene and its associated tyrosine kinase activity plays a major role in the initiation of myeloid differentiation.
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PMID:K562 leukemia cells transfected with the human c-fes gene acquire the ability to undergo myeloid differentiation. 265 6


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