Acceptor proteins for (ADP-ribose)n in the HeLa S3 cell cycle

The acceptor proteins for (ADP-ribose)n were investigated by using nuclei or chromosomes isolated from specific phases of the cell cycle of HeLa S3 cells. Analysis of HMG proteins and histone H1 by acetic acid/urea polyacrylamide gel electrophoresis demonstrated that the (ADP-ribosyl)n-ation of HMG 14 and 17 and histone H1 increased by 12- and 5-fold, respectively, in the metaphase chromosomes as compared with that in the G1 phase cell nuclei. The degree of (ADP-ribosyl)n-ation of these proteins in the S phase cell nuclei was as low as that in G1 phase cell nuclei. In the G2 phase cell nuclei, the degrees of (ADP-ribosyl)n-ation of HMG 14 and 17 and histone H1 were about 5- and 2-fold greater, respectively, as compared with that in the G1 phase cell nuclei. The (ADP-ribosyl)n-ation of HMG 1 and 2 was constant through the cell cycle except for a slight decrease in the S phase. The data may imply that the (ADP-ribosyl)n-ation of HMG 14 and 17 and histone H1 is linked to chromatin structural changes in mitosis.