Cell cycle and protein synthesis

[Dennis Goode]

Miguel,
You  asked:
> Is any protein being translated during the cell cycle 
>phases G2 and mitosis?
>Does Actinomycin D block the transition from G2 to M?

Many proteins are translated during G2, including proteins for 
entry into mitosis like cyclin, but few if any proteins are 
synthesized during the middle phases of mitosis.
(See Alberts et al. Molecular Biology of the Cell)

Actinomycin D can block mitosis if given 2 or 3 hours before, but 
has no effect on mitosis if given an hour before. What it does 
inhibit is synthesis of new proteins that appear in early G1, 
apparently from mRNAs made before mitosis and kept inactive during 
mitosis. So the low protein synthesis is not due to lack of messages.

-Dennis

Dr. M. Dennis Goode                 Phone (301) 405-6917
Department of Zoology               Fax   (301) 314-9358
University of Maryland              e-mail goode at zool.umd.edu
College Park MD 20742
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"If the Lord Almighty had consulted me before embarking upon the 
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