Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.17 (lysozyme)
 21,489 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of TPA (12-0-tetradecanoylphorbol-13-acetate) and RA (retinoic acid) were investigated on the cell lines HL60 (acute promyelocytic leukemia) and K562 (erythroleukemia) and on cells from patients with several kinds of leukemia. There were 14 cases of acute lymphocytic leukemia (ALL), 2 cases of chronic lymphocytic leukemia (CLL), 23 cases of acute myeloid leukemia (M1-M7), 5 cases of chronic myelocytic leukemia in blast crisis (CML-BC) and 2 mixed leukemias. In almost all of the cases examined, after TPA exposure cells from patients with proven myeloid leukemia became adherent to the substrate, while lymphoid leukemia cells remained in suspension, allowing the differentiation of lymphoid from myeloid blasts. The only exception was in one case of CLL, which had cells that became adherent with long filamental projections. In addition, increased phagocytosis following TPA exposure permitted characterization of M7 as this was the only myeloid leukemia negative for phagocytosis. Further discrimination between the subtypes of myeloid leukemia could be based on the increased lysozyme production seen after TPA in M4 and M5. Esterase positivity allowed the discrimination of M1 cells, which were negative before and after TPA treatment. In agreement with the results of other authors, TPA and RA led to independent ways of differentiation, granulocytic-like lineage and monocytic-like cells being favored by RA and TPA, respectively. The capacity of the same cell to differentiate into more than one lineage, depending on whether RA or TPA was used, was only seen in the present study with M3 cells.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Myeloid leukemia differentiation by phorbol ester and retinoic acid: a practical approach. 223 Nov 80

Although protein breakdown in most cells seems to require metabolic energy, it has only been possible to establish a soluble ATP-dependent proteolytic system in extracts of reticulocytes and erythroleukemia cells. We have now succeeded in demonstrating in soluble extracts and more purified preparations from rabbit skeletal muscle a 12-fold stimulation by ATP of breakdown of endogenous proteins and a 6-fold stimulation of 125I-lysozyme degradation. However, it has still not been possible to demonstrate such large effects of ATP in similar preparations from liver. Nevertheless, after fractionation by DEAE-chromatography and gel filtration, we found that extracts from liver as well as muscle contain both the enzymes which conjugate ubiquitin to 125I-lysozyme and an enzyme which specifically degrades the ubiquitin-protein conjugates. When this proteolytic activity was recombined with the conjugating enzymes, ATP + ubiquitin-dependent degradation of many proteins was observed. This proteinase is unusually large, approx. 1500 kDa, requires ATP hydrolysis for activity and resembles the ubiquitin-protein-conjugate degrading activity isolated from reticulocytes. Thus the ATP + ubiquitin-dependent pathway is likely to be present in all mammalian cells, although certain tissues may contain inhibitory factors.
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PMID:Skeletal muscle and liver contain a soluble ATP + ubiquitin-dependent proteolytic system. 282 Mar 75

A soluble ATP-dependent system for protein degradation has been demonstrated in reticulocyte lysates, but not in extracts of nucleated cells. We report that extracts of undifferentiated murine erythroleukemia (MEL) cells contain a labile ATP-stimulated proteolytic system. The addition of ATP to MEL cell extracts at alkaline pH enhances degradation of endogenous cell proteins and various radiolabeled exogenous polypeptides from 2-15-fold. Nonhydrolyzable ATP analogs had no effect. In reticulocytes, one role of ATP in proteolysis is for ubiquitin conjugation to protein substrates. MEL cells also contain ubiquitin and extracts can conjugate 125I-ubiquitin to cell proteins; however, this process in MEL cells seems unrelated to protein breakdown. After removal of ubiquitin from these extracts by DEAE- or gel chromatography, the stimulation of proteolysis by ATP was maintained and readdition of purified ubiquitin had no further effect. In addition, these extracts degraded in an ATP-dependent fashion casein whose amino groups were blocked and could not be conjugated to ubiquitin. After gel filtration or DEAE-chromatography of the MEL cell extracts (unlike those from reticulocytes), we isolated a high molecular weight (600,000) ATP-dependent proteolytic activity, which exhibits many of the properties of energy-dependent proteolysis seen in crude cell extracts. For example, both the protease and crude extracts are inhibited by hemin and N-ethylmaleimide and both hydrolyze casein, globin, and lysozyme rapidly and denatured albumin relatively slowly. The protease, like the crude extracts, is also stimulated by UTP, CTP, and GTP, although not as effectively as ATP. Also, nonhydrolyzable ATP analogs and pyrophosphate do not stimulate the protease. Thus, some mammalian cells contain a cytosolic proteolytic pathway that appears independent of ubiquitin and involves and ATP-dependent protease, probably similar to that found in Escherichia coli or mitochondria.
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PMID:A soluble ATP-dependent system for protein degradation from murine erythroleukemia cells. Evidence for a protease which requires ATP hydrolysis but not ubiquitin. 299 55

The bone marrow biopsy specimens of 35 patients with benign and malignant erythroid hyperplasias were examined for the presence of hemoglobin A, hemoglobin F, muramidase (lysozyme), and transferrin, using an indirect immunoperoxidase method (PAP) on Zenker's-fixed paraffin-embedded bone marrow biopsy specimens and particles. Five cases of each of the following entities were studied: erythroleukemia and erythremic myelosis, acute granulocytic leukemia with maturation (FAB M2), polycythemia rubra vera, myeloproliferative syndrome in childhood, megaloblastic anemia (B12 and folate deficiency), erythroid hyperplasia (regenerating bone marrow and hemolytic anemia), and Ph' chromosome positive chronic granulocytic leukemia. Hemoglobin A was present in both the early and late erythroid precursors in all conditions. Hemoglobin F was the predominant hemoglobin in early erythroblasts of pernicious anemia and in both early and late erythroid elements in erythroleukemia and erythremic myelosis. Small quantities of hemoglobin F were present in a few isolated clusters in other conditions. Staining for hemoglobin F may be useful in identifying immature erythroid precursors and in distinguishing some cases of dysplastic erythroid hyperplasia from neoplasia. Additionally, these findings suggest that the maturational switch in hemoglobin synthesis operates with distinct pathways under different conditions.
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PMID:An immunohistochemical study of hemoglobin A, hemoglobin F, muramidase, and transferrin in erythroid hyperplasia and neoplasia. 619 99