Figure 1.

Schematic presentation of wild-type βc- and βc79-constructs and positions of PCR primers. βc cDNA from exon II to exon XIV, which contains the full length of the protein coding region, was inserted into a pIREShyg2 vector that had an IVS, an internal ribosome entry site (IRES), and hygromycin resistance gene between its cloning site and poly(A) region. The distance from the normal stop codon in wild-type βc to the IVS was 254 nucleotides. The retention of 79-base intron V in βc79 caused a frameshift that generated 18 PTCs. The first termination codon in βc79 was "TGA". Hyg^r: hygromycin resistance gene, P_CMV: human cytomegalovirus major immediate early promoter/enhancer.