Human H1 histones: conserved and varied sequence elements in two H1 subtype genes.

The genes coding for two different human H1 histones were isolated, and the primary structures were deduced from the nucleotide sequences. The genes differ from each other and from any other vertebrate H1 structure described until now. The differences occur mainly within the N- and C-terminal H1 domains, whereas the central part of the protein is highly conserved. Within the flanking domains, however, some sequence elements are shared by different H1 subtype genes. An octapeptide, which has been described in C-terminal domains of most H1 histones, is found in both H1 subtypes. The nucleotide sequences of the flanking portions of both H1 genes show conserved motifs at established regulatory sites, but otherwise these 3' and 5' noncoding sequences of both genes differ substantially.