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. 2012 Nov 26;109(50):20449–20454. doi: 10.1073/pnas.1210983109

Fig. 1.

Fig. 1.

(A) Schematic representation of a GagPol polyprotein precursor of HIV. GagPol is composed of a linear heteropolymer chain. Only a single monomer of protease (PR) is present on each GagPol chain. Mature protease cleaves GagPol at recognized cleavage sites between proteins. (B) Schematic representation of transient dimerization of two GagPol chains to form an embedded protease dimer. This precursor autocatalyzes its own liberation into the mature form of the dimeric protease that consists of natively folded N-terminal (cyan) and C-terminal (orange) chains in an interdigitated four-stranded β-sheet. A pair of β-hairpin structures termed the “flaps” (red) mediate active site access. (C) Structural representation of N-terminal (N-ter) construct (cyan) of immature HIV-1 protease, with 5-aa (VFSNF) extension corresponding to the p6-PR cleavage site. An unstructured hinge region connects the tertiary structure to the N-ter region.