CDNA sequences are available for several aminopeptidases and a crystal structure of the open state of human endoplasmic reticulum Aminopeptidase 1 ERAP1 is presented here.
RNA polymerase is then used to generate long double stranded RNA that is homologous to the target-gene cDNA.
The technique has largely been supplanted by the approach of sequencing cDNA generated from mRNA and then using bioinformatics tools such as NCBI's BLAST server to determine the source of the sequence, thereby identifying the appropriate exon-intron splice sites.
The cDNA coding for rasburicase was cloned from a strain of Aspergillus flavus.
The newly formed cDNA in the two tubes are cut with a restriction endonuclease such as DpnII.