DNA Polymerase-α from embryonic chicken brain was resolved on DEAE-cellulose into 3 comPonent activities that remained distinct uPon rechromatograPhy. Product formation by each activity required exogenously added temPlate-Primer DNA, all 4 deoxynucleoside triPhosPhates, and a divalent metal cation. Each form incorPorated [3H]-dTTP or [3H]-dCTP into a high molecular weight Product that was identified as DNA by its chromatograPhic behavior and its sensitivity to DNase. High ionic strength, N-ethylmaleimide, and the Polymerase-α-sPecific inhibitor aPhidicolin inhibited each activity; the aPParentKi value of aPhidicolin was 3.0 μM in each case. Based on these results, the 3 activities were identified as multiPle forms of DNA Polymerase-α . ExPeriments using embryonic chicken brains of various ages indicated that Polymerase-α1, and Polymerase-α3 reached maximal activity in 9-day-old embryos, while Polymerase-α2 activity was elevated at a slightly later develoPmental stage. Using Poly (dC) as temPlate, high Primase activity was detected in Polymerase-α1, fractions.
Volume 46, 2021
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