Figure 5.

Expression of the TPR domain of SPY does not affect the expression of the endogenous SPY gene. RT-PCR was used to quantitate the amount of SPY mRNA present in wild-type plants and three lines expressing the SPY TPR domain. Each reaction contained primers that amplify both cDNA derived from the endogenous SPY mRNA (SPY) and UBIQUITIN 3 mRNA (UBQ3) and was terminated when the amplification of both products was linear with respect to cycle number (see “Materials and Methods”). The primers to the SPY mRNA do not amplify the mRNA that encodes the TPR domain of SPY. An autoradiogram of a blot containing the PCR products that was probed with ³²P-labeled SPY and UBQ3 probes is shown. The signal from each product was quantitated and the number above each lane indicates the ratio of the hybridization to RT-PCR products. Because both sets of primers flank introns, the products from genomic DNA will be larger than the products from cDNA. No product from genomic DNA was detected in any experiment.