Change of nuclear protein phosphatase activity in the liver of old rats

Nuclear protein phosphatase (NPP-ase) activity was measured in non-histone protein (NHP) preparations obtained from liver nuclei of young and old rats with exogenous substrates labelled with 32P. NPP-ase activity can be measured in a rather broad range of pH between 5.5 and 7.5 and it shows several...

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Bibliographic Details
Published in:Experimental gerontology 1981, Vol.16 (2), p.171-176
Main Authors: Viticchi, C., Szeszák, F.
Format: Article
Language:English
Subjects:
Aging
Animals
Liver - enzymology
Male
Phosphoprotein Phosphatases - metabolism
Phosphorylation
Rats
Rats, Inbred Strains
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Summary:Nuclear protein phosphatase (NPP-ase) activity was measured in non-histone protein (NHP) preparations obtained from liver nuclei of young and old rats with exogenous substrates labelled with 32P. NPP-ase activity can be measured in a rather broad range of pH between 5.5 and 7.5 and it shows several characteristic differences between young (4–6 months) and old (24–28 months) animals: (a) under the effect of NPP-ase a limited dephosphorylation of nuclear phosphoprotein (NPP) substrate ensues reaching a 25 per cent liberation maximum of incorporated 32P in the case of NHP preparations from young animals; the same liberation maximum is over 45 per cent in the case of old animals, (b) an age-related change of NPP-ase activity is assumed to occur in old rats in comparison with young ones. The NPP-ase activity measurable for its homologous—NPP—substrate increases in old animals while there is a concomitant decrease of casein phosphatase activity. The possible implication of the phosphorylation of chromosomal non-histone proteins in the cellular aging is discussed.
ISSN:0531-5565
1873-6815
DOI:10.1016/0531-5565(81)90042-5