Schematic view of L3/p23 protease-inactivated Ad2 and Ad2-ts1 lacking functional protease.  If the cysteine protease L3/p23 is chemically inactivated in isolated virus, Ad2 progresses to the nuclear pore complex, but fails to dissociate the capsid.  The mutant Ad2-ts1, in turn, not only lacks functional protease but also contains an immature, nonproteolyzed capsid.  Ad2-ts1 is defective at the endosome escape step.  Modified from (1).

(1). Greber, U. F., et al. (1996) EMBO J. 15, 1766-1777.