Homology of nuclear factor I with the protein kinase family

It is observed that a putative DNA binding domain in nuclear factor I (NF I) which is a eukaryotic sequence-specific DNA binding protein participating in both regulation of DNA replication and transcription displays sequence homology with catalytic domains in various protein kinases. In addition, hydropathy analysis reveals that the NF I polypeptide chain is likely to fold into similar secondary and tertiary structures to those of the protein kinases. Although it is not known whether NF I functions as a protein kinase in addition to recognizing a specific sequence on DNA, it is concluded that some of the eukaryotic DNA binding proteins and protein kinases may belong to a gene family, various members of which are evolutionarily related and responsible for the regulation of metabolism in diverse compartments of the cell. The present finding also suggests that a number of kinases may to varying extents be capable of direct interaction with DNA.