Department of Cell Biology
Medical Subject Headings
Electrophoresis, Disc; Hela Cells; Kinetics; Leucine; *Mitosis; Nucleoproteins; Proteins; Thymidine; Time Factors; Tritium
The kinetics of acidic residual chromosomal protein synthesis and transport were studied throughout the cell cycle in HeLa S-3 cells synchronized by 2 mM thymidine block and selective detachment of mitotic cells. Pulse labeling the cells with leucine-(3)H for 2 min and then "chasing" the radioactive proteins for up to 3 hr showed that the amount of protein synthesized, transported, and retained in the acidic residual chromosomal protein fraction is greater immediately after mitosis and later in G(1) than in the S or G(2) phases of the cell cycle. During S, only 20-25% of the proteins synthesized and transported to the acidic residual chromosomal protein fraction are chased during the first 2 hr after pulse labeling, whereas up to 40% of the material entering the residual nuclear fraction in mitosis, G(1), and G(2) leaves during a 2 hr chase. Polyacrylamide gel electrophoretic profiles of these proteins, at various times after pulse labeling, reveal that the turnover of individual polypeptides within this fraction has kinetics of synthesis and turnover which are markedly different from one another and undergo stage-specific changes.
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Citation: J Cell Biol. 1972 Feb;52(2):308-15. Link to article on publisher's website
Borun, Thaddeus W. and Stein, Gary S., "The synthesis of acidic chromosomal proteins during the cell cycle of HeLa S-3 cells. II. The kinetics of residual protein synthesis and transport" (1972). Stein, Stein, Lian, vanWijnen Lab Publications. 229.