Design and function of the ORF vector pYEXTSH3. (A) pYEXTSH3 includes a tandem epitope tag, a translation start and stop codon, and the HIS3 marker gene, which is under the control of theCUP1 promoter. In this plasmid, translation terminates before reaching HIS3. (B–D) The cloning of cDNAs insert, represented as XXXn, results in the following outcomes at the C terminus: (B) If the size of the cDNA insert is a multiple of three and both N and C termini are cloned in the correct reading frame,HIS3 is translated. (C) The translation terminates after translation of a few triplets in HIS3, if the insert is a multiple of 3 + 1, as the reading frame is shifted. (D) If the cloned cDNA includes an internal stop, there is no translation ofHIS3.
