[Increased expression of genes coding for replication proteins during the period of DNA synthesis].

Individual mRNA coding for proteins of the alpha-polymerase complex were isolated from replicating hepatocytes. cDNAs were synthesized by reverse transcriptase. Three clones were identified by colony hybridization of the S period cDNA library. The sequences of these clones were complementary to the investigated mRNAs. Two clones named pr12 and pr167 revealed increased expressions in the S period. The level of mRNA pr127 does not change during liver regeneration. The amount of pr127 mRNA was about 1% of the total mRNA population. pr12, pr127 and pr167 mRNAs were isolated by the hybrid-selection method and were translated in a cell-free system. The products of translation were analysed by "activity" gel. It was shown that pr167 mRNA coded for protein 140 kDa with DNA polymerase activity. pr12 protein is an unknown component of the alpha-polymerase complex. We suggested that this protein participates in the initiation of DNA replication.