Cell Growth & Differentiation, Vol 2, Issue 11 567-573, Copyright © 1991 by American Association of Cancer Research
Developmental expression of the embryonic chicken brain DNA polymerase alpha and its binding with monoclonal antibodies against human KB cell DNA polymerase alpha
S Ray, TJ Kelley, S Campion, AP Seve and S Basu
Department of Chemistry and Biochemistry, University of Notre Dame, Indiana 46556.
Changes in DNA polymerase alpha activity accompanying tissue development
have been well established in several systems. In most cases, DNA
polymerase alpha activity decreases with development. Here, we report
observed changes in DNA polymerase alpha activity throughout embryonic
chicken brain (ECB) development. The level of DNA polymerase alpha activity
was found to gradually decrease by 60% (2.3 to 0.8 nmol of [3H]dCMP
incorporated/mg protein/h) between 9- and 19-day-old ECB. An enzyme-linked
immunosorbent assay of DNA polymerase alpha utilizing monoclonal antibody
SJK 237-71 (human KB cell DNA pol-alpha binder) also demonstrated a gradual
decrease (up to 60%) of antigen over this same range of development.
Analysis of DNA polymerase alpha from 11- and 19-day-old ECB by a 10 to 30%
glycerol density gradient revealed a high molecular weight peak sedimenting
near catalase (11.3 S) with activity at the 11th day being approximately
3-fold greater than activity at the 19th day. A Western immunoblot analysis
utilizing monoclonal antibody SJK 237-71 (against human KB cell DNA
polymerase alpha) showed a decrease in DNA polymerase alpha from 186
kilodaltons in 9- and 11-day ECB cell-free extracts to 120 kilodaltons in
extracts from 13- to 19-day ECB. The conversion of DNA polymerase alpha
from a higher to a lower molecular weight form may be a regulatory
mechanism in eukaryotic DNA replication.