RNA Splice Site Selection: Evidence for a 5′ → 3′ Scanning Model

Human G gamma-globin genes containing tandem duplications of the donor (5') or acceptor (3') RNA splice sites of the second intervening sequence were constructed in order to ascertain the directionality of RNA splice site selection. These genes were introduced into cultured monkey cells, and their transcripts were analyzed. Transcripts of these duplication variants were spliced only at the proximal copy of the duplicated splice sites. These data are consistent with a 5' leads to 3' model of splice site selection.