Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.26.9 (ribonuclease)
 6,589 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Inability to culture the disease-producing amastigote form of Leishmania has greatly hampered its study. We have biochemically characterized an axenically cultured amastigote-like form of Leishmania pifanoi. This form closely resembles amastigotes in proteinase, ribonuclease, adenine deaminase and peroxidase activity. It also exhibits comparable rates of growth, transformation, synthesis of DNA, RNA and protein, and metabolism of glucose and linoleic acid. It is distinct from promastigotes in these characteristics. The expression of the genes for beta-tubulin and the P100/11E reductase is developmentally regulated in this axenic form as in amastigotes. These results, combined with previous demonstrations of amastigote morphology and antigenicity in the culture form, confirm that Leishmania amastigotes have been successfully propagated in axenic media. This strain should serve as an excellent model for the study of amastigote biochemistry, pharmacology and immunology, and the molecular genetics of the transformation between amastigote and promastigote forms.
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PMID:Biochemical and molecular characterization of Leishmania pifanoi amastigotes in continuous axenic culture. 177 52

Total HeLa cell extract was separated into multiple components using first DEAE-Sephadex and then phosphocellulose column chromatography. Four major fractions, DE175, DE500, P100, and P1000, from HeLa cells are found to be essential for accurate and efficient transcription of cloned ovalbumin DNA fragments in the reconstituted system. DE175 serves as the source for RNA polymerase II and DE500 minimizes the synthesis of small molecular size RNA. P100 enhances the levels of specific transcription, while P1000 is absolutely required for correct initiation. Chick oviduct crude extract was also fractionated into multiple components according to the same procedure. Similar efficiency of specific initiation could be obtained when an individual fraction (DE175, DE500, P100, or P1000) from oviduct cells was exchanged for a fraction from HeLa cells. These results indicate that chick oviduct tissue also contains general transcription factors like that of HeLa cells and these factors can be fractionated according to the same procedure. In this fractionation scheme, we were able to separate the bulk of RNase activity into the P350 fraction which was not required for initiation of ovalbumin RNA transcription. Thus, this reconstituted system is suitable for studying in vitro transcription in a homologous system derived from tissue extracts, even though a substantial amount of cellular ribonuclease may be associated with it.
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PMID:Transcription factors from oviduct and HeLa cells are similar. 689 17