Gene specific priming of complementary DNA synthesis

DNA, complementary to chicken globin mRNA was synthesized using either Avian Myeloblastosis virus reverse transcriptase, or E. coli DNA polymerase I. Transcriptase cDNA sediments at 9 S on sucrose gradients, and is 620 nucleotides in length, representing a complete copy of globin mRNA template. In contrast, Polymerase I cDNA sediments at 4 S, is 100 to 200 nucleotides in length, and is a copy of a small region at the 3'(poly A) end of globin mRNA. Similarly, Transcriptase cDNA and Polymerase I cDNA hybridize to globin mRNA template with characteristic, individual Crot1/2 values. The Crot1/2 value for Transcriptase cDNA hybridization is 7 X 10(-4) mol s 1(-1), and that for Polymerase I cDNA is 5 X 10(-3). This work shows that Avian Myeloblastosis virus reverse transcriptase can use Polymerase I cDNA to prime further cDNA synthesis along the mRNA template. The product of extended cDNA synthesis is identical in length and hybridization properties to oligo (dT) primed transcriptase cDNA.