Figure 1. Schematic representations of PAX6 and PAX6(5a) and plasmids used as internal standards

A: Structure of PAX6, 422 amino acids and PAX6(5a), 436 amino acids. Exon 5a encodes a 14 amino acid insertion into the PAI subdomain of the paired domain disrupting its ability to bind DNA. RED subdomain and homeodomain (HD) are also shown. B: Internal standards (mimics) were created by subcloning three copies of a synthetic oligonucleotide into a unique Pst I site of the PAX6 and PAX6(5a) PCR generated fragments in pBluescript SK II as described in the Materials and Methods. The sizes of PCR products for PAX6, mimic PAX6, PAX6(5a) and mimic PAX6(5a) are 289, 431, 331, and 481 bases, respectively.