Figure 4

Alternative splicing of Abcg8 mRNA expression in SD, SHR and WKY rats by RT-PCR Panel A shows the gene organisation of Abcg8, and below it the organisation of an alternatively spliced form detected by sequencing clones from a rat intestinal cDNA library (see Text). Panel B shows that the effect of the inclusion of exon 2b in the mRNA results in an in-frame addition of 22 amino acids. Total RNAs were prepared from liver and small intestine from SD, SHR and WKY rats maintained on a standard rodent chow diet and analysed by RT-PCR with primers (see Methods) based outside the alternatively spliced exon 2b. Direct amplification of a pooled cDNA library sample indicated a major DNA product of 396 bp, with a minor product of 462 bp, containing exon 2b. DNA products, using cloned wild type Abcg8 cDNA (wt) and alternatively spliced cDNA (AS) are shown in tracks 3 and 4 respectively. As can be seen, liver and intestine RNA from all three strains show a minor DNA product of 462 bp (confirmed by sequencing) contained the insertion of exon2b sequences.