The reverse transcriptase employs a "right hand" structure similar to that found in other viral nucleic acid polymerases. In addition to the transcription function, retroviral reverse transcriptases have a domain belonging to the RNase H family, which is vital to their replication. By degrading the RNA template, it allows the other strand of DNA to be synthesized. Some fragments from the digestion also serve as the primer for the DNA polymerase (either the same enzyme or a host protein), responsible for making the other (plus) strand.