Relative ratios of mRNA molecules encoded by genes with homologous sequences using fluorescence-based single-strand...

The combination of reverse transcribed (RT)-PCR and fluorescence-based single-strand conformation polymorphism (SSCP) analysis is proposed for the quantitative determination of the ratio of mRNA molecules with homologous sequences. We applied this procedure to lactate dehydrogenase (LDH) subunits A and B. We designed fluorescence labeled common PCR primers in the sequences highly homologous between LDH-A and LDH-B cDNAs and performed RT-PCR-SSCP analysis. When PCR efficiency was almost the same between the different target sequences, analysis of mixtures of known amounts of LDH-A and LDH-B revealed linear and precise proportions of LDH-A mRNA. Template concentrations and PCR cycles did not affect the determination of proportions of LDH-A to total LDH. The present procedure could be easily applied to investigation of expression levels of genes encoding mRNAs with homologous sequences.