FIG 1.

Schematic diagram of the HIV-1 Gag cleavage and maturation process. WT virions mature through the 4 stages shown on the top row, with ∼95% of them assembling a capsid, 80% to 85% of which are conical (top row, right diagram). (In the remaining ∼5%, which lack a core, all of CA stays in the soluble pool [top row, third diagram].) In MI-treated virions (11, 15), much of the CA (typically, 50% or so [42]) remains in an immature-like lattice (bottom row, left diagram). Therefore, the size of the immature-like lattices is reduced compared to that of the immature ones. In CA5 virions, in which CA-SP1 cleavage is completely blocked, the CA shell progresses to a mature-like conformation (bottom row, right diagram). (Bottom left) Diagram showing the SP1 sequence, with the Thr at residue 8 of SP1 that is mutated to Ile in the T8I mutant underlined, and the secondary cleavage site marked with an arrowhead. Note that SP2 and p6 (distal to NC [4, 43]) are not included in these diagrams.