Figure 3.

Exon sequence influences splicing phenotype. APRT genes containing an expanded MT exon similar to those described in Fig. 1A were created in which the exon expansion cassette was derived from either chicken OVA (A) or human HPRT (B) cDNAs. RNA splicing phenotypes were determined by RT-PCR as described in Fig. 1. Products resulting from skipping or inclusion of the middle exon are indicated. The unexpected products in B from the constructs with middle exons of 556 or 894 nt are indicated with an arrow and were sequenced. The splicing patterns as determined from sequencing data are depicted below the figure. Both gels were silver-stained to visually emphasize inclusion products. The cryptic spliced transcripts produced in B are denoted with an arrow.