Primer Extension System---AMV Reverse Transcriptase can be used to quantitate specific mRNA transcripts and map the start sites of transcription. An end-labeled oligonucleotide is hybridized to RNA and is used as a primer by reverse transcriptase in the presence of deoxynucleotides. The RNA is thus reverse transcribed into cDNA and is analyzed on a denaturing polyacrylamide gel. The length of the cDNA reflects the number of bases between the labeled nucleotide of the primer and the 5'-end of the RNA; the quantity of cDNA product is related to the amount of targeted RNA.
