Alternative sites of transcription initiation upstream of the canonical cap site in human gamma-globin and beta-globin genes.
Using S1 mapping and primer extension analysis, we have identified a number of human kappa-globin and beta-globin 5' RNA termini originating in the 200 bp upstream of the canonical mRNA cap sites. Upstream initiation sites have previously been reported for the human epsilon-globin gene (4,5) and the present work indicates that this is a general feature of the human beta-type globin genes. We have attempted to identify features common to such sites between the three genes. One site 170 bp upstream of the major beta-globin cap site and a site 1400 bp upstream of the major epsilon-globin cap site are located near putative PolIII promoter sequences and may therefore be transcribed by this enzyme. Alternative initiation sites located 200 bp and 50-100 bp upstream of the epsilon-globin and kappa-globin cap sites respectively are located within S1 hypersensitive regions of chromatin.
D001482:Base Composition; D001483:Base Sequence; D002843:Chromatin / Q000502:physiology; D005796:Genes; D005914:Globins / Q000235:genetics*; D006801:Humans; D009693:Nucleic Acid Hybridization; D009876:Operon; D012333:RNA, Messenger / Q000235:genetics*; D014158:Transcription, Genetic
D002843:Chromatin; D012333:RNA, Messenger; D005914:Globins