 The HIV-1 RT is an asymmetric 1000-amino acid heterodimer composed of p66 (560 amino acids) and p51 subunits (440 amino acids).The p66 subunit has two domains, a polymerase and ribonuclease H. The polymerase domain contains four subdomains, which have been termed “fingers”, “palm”, “thumb” and “connection” and it is often compared to a right hand (figure 1).The role of the p66 subunit is to carry out the activity of RT whereas it contains the active sites of the enzyme.