HIV must use a HIV encoded enzyme
called protease in order to cleave a large Gag-Pol polyprotein (p120), a
Gag polyprotein (p55), and an Env polyprotein (gp160) into functional proteins
essential to the structure of HIV and to its RNA packaging. The active site
of the HIV protease binds to the polyproteins and cleaves them into the functional
proteins needed for viral replication and maturation.
The Gag polyproteins (p55)
will eventually be cleaved by HIV proteases to become HIV matrix proteins
(MA; p17), capsid proteins (CA; p24), nucleocapsid proteins (NC, p7), and protein p6.
The Gag-Pol polyproteins (p160)
will eventually be cleaved to become HIV matrix proteins (MA; p17), capsid
proteins (CA; p24), proteinase molecules (protease or PR; p10), reverse
transcriptase molecules (RT; p66/p51), and integrase molecules (IN; p32).
The Env polyproteins (gp160) will eventually be cleaved to become HIV envelope
glycoproteins gp120 and gp41.