Late protein responsible for processing most or all of the viral core and membrane proteins known to undergo morphogenesis-associated proteolysis. These proteolytic events are involved in the transformation of immature virions (IV) into mature virions (MV). Probably cleaves at least the A3, A10, L4, and A17 precursors preferentially at Ala-Gly-|-Ala motifs. Also seems to process Ala-Gly-|-Ser and Ala-Gly-|-Thr motifs (By similarity). Present in the virion core. Expressed late in the viral replicative cycle. Belongs to the peptidase C57 family.