[HMG protein levels in cell nuclei with different proliferative and transcription activities]

It is shown that HMG1 and HMG2 proteins are present in the nuclei of the both actively proliferating and resting lymphocytes in the equally high amount. On the other hand, the same proteins are almost or even completely absent from the nuclei of all kinds of hepatocytes studied: nonproliferating hepatocytes from calf and rat liver and actively proliferating cells from rat regenerating liver and primary hepatoma. These results reveal a tissue specific distribution of HMG1 and HMG2 proteins and do not confirm the suggestions that HMG1 and HMG2 proteins are necessarily involved in chromatin replication or transcription. In contrast, HMG14 and HMG17 proteins have not shown the tissue specificity in our experiments. Besides, the content of these two proteins does not depend on the actual transcriptional activity of the tissues. These results confirm the suggestion that HMG14 and HMG17 proteins are present not only in the genes that are actually being transcribed, but in a broader set of genes.