Figure 1.

Description of hCAR isoforms. (A) Diagram detailing the hCAR protein structure aligned to the exonic regions of the corresponding mRNA, the DNA-binding domain (DBD), the hinge domain (H) and the ligand-binding domain (LBD), respectively. (B) A schematic representation (top) of hCAR exons 1–9 in the context of the gene (our unpublished observations and Locuslink ID no. 9970/genomic contig: NT_026945). The region of mRNA that demonstrates the alternative splicing events identified in this study, exons 7, 8 and 9, is depicted in greater detail. The sizes of the introns and exons noted above and below the amplified schematic are derived from the reference isoforms, obtained from the Locuslink data (as above). The mRNA isoform containing the 12 bp insertion is generated by an alternative splice acceptor site within intron 6 leading to a 5′ extension of exon 7. Incorporation of these nucleotides leads to an in-frame 4 amino acid insertion. The mRNA isoform containing the 15 bp insertion is generated by an alternative splice acceptor site within intron 7 leading to a 5′ extension of exon 8. Incorporation of these 15 nucleotides leads to an in-frame 5 amino acid insertion. Individual clones that contained both the 12 and 15 bp insertion were also identified. An additional mRNA isoform is generated by the complete removal of exon 7, leading to an in-frame deletion of 39 amino acids. (C) Detail of the nucleotide sequence surrounding the splice junctions between exons 6 and 7 (top) and exons 7 and 8 (bottom). Reference sequences are represented in upper case letters, and incorporated nucleotides due to alternative splicing are represented by lower case letters. Canonical splice donor and splice acceptor sites present in the genomic DNA are shown in bold lower case. The reading frame of each sequence is shown below each sequence. Splice acceptor sites are indicated by arrows. (D) ClustalW alignment of the predicted hCAR isoform amino acid sequences, Reference, 4aaINS, 5aaINS and 39aaDEL (53).