Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.8 (polynucleotide phosphorylase)
 723 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Specific activity and level of polynucleotide phosphorylase (PNPase) in polyribosomes of regenerating liver of adult rats, liver of newborn rats and in malignant tumours of rat (sarcoma M-1 and hepatoma 27) were studied. 24 hours after partial hepatectomy the specific activity and level of PNPase in regenerating liver decreased 3--4 times in the fraction of polyribosomes, bound to the endoplasmic reticulum membranes, and remained at a constantly low level in the fraction of free polyribosomes. The PNPase activity also showed a sharp decrease in the fraction of membrane-bound polyribosomes from newborn rats liver and could not be detected either in free or in bound polyribosomes from sarcoma M-1 or hepatoma 27. The PNPase activity in the fraction of bound polyribosomes increased with a decrease in the rate of liver growth (regenerating liver and newborn rats liver), and reached the level normal for adult animals. Possible mechanisms of regulation of the PNPase activity in animal tissue were studied. It was found that a 2-fold administration of cyclic 3,5'-AMP to intact animals (5 mg per 100 g of body weight) with an interval of 8 hours, corresponding to the interval between two peaks of the increase in cyclic 3,5'-AMP concentration following partial hepatectomy, diminished the PNPase specific activity in polyribosomes by 30%. A factor, presumably of protein origin, which induced a release of PNPase from polyribosomes of normal rat liver but did not affect the activity of the liberated enzyme, was detected in the cell sap of sarcoma M-1 and hepatoma 27.
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PMID:[The activity of polynucleotide phosphorylase in polyribosomes of regenerating liver of adult rats, liver of newborn rats and in some reinoculated tumours]. 19 Nov 6

The capacity of the partially purified preparation of the polynucleotide phosphorylase releasing factor (PNP-ase RF) from Walker sarcoma for stimulating the growth of hybrid cells and parent myeloma cells has been studied. The preparation of PNP-ase RF at a concentration of 500-50 micrograms/ml has been shown to induce the 3- to 10-fold increase of the number of cells in the culture by the 5th day of incubation without changing the medium.
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PMID:[Capacity of the polynucleotide phosphorylase-releasing factor to stimulate hybrid cell growth]. 371 92

A releasing factor (RF) of polynucleotide phosphorylase (PNPase) isolated and purified from sarcoma M-1 of the rat is a protein with molecular weight of about 8000 and the isoelectric point at 4,0--4,2. The process of PNPase release from the polyribosomes of normal rat liver does not depend on the pH of the medium within the pH range of 7,2--9,0, on temperature within the interval of 0--400 degrees and on incubation time. Inhibition of phosphorolysis by endogenous RNA from normal rat liver polyribosomes requires considerable amounts of RF--approximately 170--800 molecules of RF per molecule of poly(A)+-mRNA. The data obtained suggest that PNPase release from the polyribosomes under the action of RF is not a catalytic process and is caused by competition between RF and PNPase for the binding sites on the mRNA molecule.
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PMID:[Purification and properties of a releasing factor of polynucleotide phosphorylase from sarcoma M-1 of rat]. 737 90