On the 'active' molecules of DNA-polymerase beta in aging rat brain.

DNA polymerase beta, a 38kD protein is essentially considered to be a repair enzyme at least with respect to some forms of DNA damage. Through northern and western blotting, it was found that mRNA and immunologically reactive molecules of DNA-polymerase beta are reduced by 30% and 20% respectively in old rat brain as compared to the young. However, activity gel assay and immunotitration revealed a 50% reduction in the activity in old brain. These data are taken to indicate accumulation of catalytically inactive molecules of DNA-polymerase beta in rat brain with age.