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

Coupled transcription and translation of plasmid-ColE1 DNA in vitro under optimized conditions gave one major product. This has an apparent weight of 71 000, the same N-terminal sequence as colicin E1 and was not digested by deoxyribonuclease or ribonuclease. It differed from colicin E1 in its C-terminal residue and amino acid composition. It had lower specific activities in cell killing and in the fluorescence-enhancement in vitro assay of Phillips & Cramer [(1973) Biochemistry 12, 1170--1176] than did colicin E1, but both proteins bound in equimolar amounts to colicin-sensitive and colicin-resistant cells. The product of plasmid-ColE1-DNA-directed protein synthesis was converted into a protein indistinguishable in structure and activity from colicin E1 by incubation in the reaction mixture, after deoxyribonuclease and ribonuclease treatment, for a further 20 h at 37 degrees C. A protein with similar properties to the 71 000-dalton product in vitro was identified in extracts of a ColE1+ colicin-tolerant mutant of Escherichia coli K12. It is concluded that this protein probably represents a pre-form of colicin E1 which may be involved in colicin-E1 secretion or cellular colicin-E1 immunity in colicin-E-producing cells, or both of these processes.
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PMID:Precolicin E1, the major gene product of plasmid-ColE1 deoxyribonucleic acid in vitro. 699 10

The DHD/K12/PROb rat colonic epithelial cell line, which was originally derived from a chemically induced adenocarcinoma, expresses functional glucocorticoid receptors (GR) and has been reported to be growth inhibited by glucocorticoid agonists. In the present study the potential mechanisms underlying corticosteroid-mediated autoregulation of GR mRNA levels in this colonic cell line were investigated. The GR mRNA levels in the various treatment groups were quantitated via the ribonuclease protection assay using a specific 32P-cRNA probe. Time-course experiments demonstrated that in contrast to several other cell lines that are also growth inhibited by glucocorticoids, treatment of confluent monolayers of PROb cells with the pure GR agonist RU 28362 (1 microM) elicits a rapid and significant (65%) down-regulation of GR mRNA levels that is sustained for at least 36 h. This down-regulation, which is also elicited to a lesser extent by weaker GR agonists including corticosterone and aldosterone, is blocked by the GR antagonist RU 38486. The protein synthesis inhibitor cycloheximide was utilized to demonstrate that the initial phase (6 h) of agonist-mediated down-regulation occurs independently of ongoing protein synthesis, although new protein synthesis, perhaps of the GR protein itself, is required to maintain this down-regulation. Although agonist-mediated down-regulation in these cells probably occurs primarily at the level of GR gene transcription, inhibition of ongoing RNA synthesis with actinomycin D or 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) demonstrated that during the initial phase (1 h) of this down-regulation, but not following maximal (18 h) down-regulation, RU 28362 treatment also significantly reduces the stability of the GR mRNA.
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PMID:Potential mechanisms underlying autoregulation of glucocorticoid receptor mRNA levels in the DHD/K12/PROb rat colonic adenocarcinoma cell line. 749 1

Four new basic proteins were isolated from horse eosinophils and purified. The eosinophils release these proteins after permeabilization with saponin and degranulation stimulized by guanosine 5'-O-thiotriphosphate. The proteins were separated and purified on a Superose P12- and a Mono S-column by fast protein liquid chromatography. The amino acid composition, the relative molecular mass, the isoelectric point and the partial N-terminal sequence of the four proteins were determined. Papain-activation and ribonuclease activity of the four proteins were tested for comparison with the human eosinophil basic granular proteins. The cytotoxicity of the hole granular extract and of the isolated basic proteins against Escherichia coli K12 was also studied.
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PMID:Isolation and characterization of four basic proteins from horse eosinophilic granules. 848 50