Gag is a polyprotein and is an acronym for Group Antigens (ag).

Pol is the reverse transcriptase.

Env in the envelope protein.

The group antigens form the viral core structure, RNA genome binding proteins, and are the major proteins comprising the nucleoprotein core particle. Reverse transcriptase is the essential enzyme that carries out the reverse transcription process that take the RNA genome to a double-stranded DNA preintegrate form. The molecular gymnastics of the latter process are outlined below. The reverse transcriptase gene also encodes an Integrase activity and an RNase H activity that functions during genome reverse transscription.