Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
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.
...
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
Amoung of prelabelled mRNA was unaltered in Zajhdel ascites
hepatoma
of rat cells within 3.5-4 hrs under conditions of treatment with actinomycin D. Due to combined effect of actinomycin D and cycloheximide the content of mRNA in the
hepatoma
cells was rapidly decreased. Degradation of mRNA occurred in membrane-bound polyribosomes, free polyribosomes and in cytoplasmic mRNP-particles /informosomes/ as a result of the effect of cycloheximide. Simultaneously with these phenomena, distinct increase in activity of acid and alkaline RNAases was observed in cytoplasma of the
hepatoma
cells; activity of endoRNAase from membrane-bound and free polyribosomes of the
hepatoma
was also markedly increased. Cycloheximide did not affect the activity of
polynucleotide phosphorylase
in polyribosomes of the
hepatoma
cells. Labile proteins, responsible for inhibition of RNAses appeart to participate in regulation of mRNA stability in malignant cells.
...
PMID:[mRNA breakdown in tumor cells in vivo under cycloheximide protein synthesis inhibition]. 51 39
