Possible involvement of a ubiquitous and several distinct elements in the transcription regulation of the chicken H3 histone gene family.

We have studied possible modes of transcription regulation of four members (H3-II, H3-III, H3-IV and H3-V) of the twelve chicken H3 genes. Results of transient CAT assays using 5'-truncated mutants of H3-IV, together with those reported previously for H3-II and H3-III, indicated that all these four H3 genes possessed a ubiquitous element, the CCAAT sequence, in addition to several distinct elements. Transient CAT assays using the 5'-extended mutants of these four H3 genes showed that the promoter activities decreased with increasing lengths of the 5'-extended fragments, and that the effects were strong for H3-IV and H3-V, but only moderate for H3-II and H3-III.