Alternative splicing of erythroid specific exon 16.

(A) Model of the splicing switch that accompanies erythroid differentiation. Constitutive exons are filled in in black; alternatively spliced E16 is filled in in gray. Early erythroid progenitors skip E16 almost entirely, while later progenitors include E16 with high efficiency. (B) Structure of the 1.2-kb minigene that serves as template for transcription of pre-mRNA splicing substrates. Arrow indicates start site for in vitro transcription.