Reverse transcriptase performs several different
functions. As indicated by the name, it can build DNA strands based on an RNA
template. This reaction is performed in the polymerase active site, which is
formed by two sets of arms that surround the RNA and DNA. The polymerase site is
at the top in this illustration, taken from PDB entry 2hmi.
After building the DNA strand, the enzyme then removes the original RNA strand
by cleaving it into pieces. This is performed by a nuclease active site, which
is located at the opposite end of the enzyme. Finally, it builds a second DNA
strand matched to the one that was just created to form the final DNA double
helix. This reaction is also performed by the polymerase site.
