The Journal of Cell Biology, Vol 87, 629-632, Copyright © 1980 by The Rockefeller University Press
Tyrosine aminotransferase sensitivity to bromodeoxyuridine during restricted intervals of S phase in hepatoma cells
JC O'Brien
Synchronized hepatoma tissue culture (HTC) cells, accumulated at the G1/S
boundary with aminopterin, were released into S phase with either thymidine
or 5-bromodeoxyuridine (BUdR). Tyrosine aminotransferase (TAT) activity was
found to be unaffected by BUdR over the initial 3 h of S phase, but then to
rapidly decline to a new basal level of 40% of control by 9 h. There was no
corresponding response in the activities of alcohol dehydrogenase, malate
dehydrogenase, acid phosphatase, and alkaline phosphatase, or in the rate
of protein and RNA synthesis. If BUdR incorporation was restricted to
limited periods of S phase, TAT was found to be maximally suppressed by
incorporation into the initial 40% of the DNA. Incorporation of the
analogue into the latter 60% of DNA synthesized during S phase had no
effect on TAT. This is the first report that the effect of BUdR on TAT in
HTC cells is associated with incorporation of the analog into DNA
synthesized during a specific interval of S phase.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Facebook 
Reddit 
Technorati 
Twitter What's this?
