Fig. 5.

Susceptibility of target ISVPs to promotion in trans is temperature dependent. Aliquots of WT T1L ISVPs were preconverted at 52°C, chilled on ice, and supplemented with an equal part of T1L ISVPs (L*→L), T3D ISVPs (L*→D), or ISVPs of the heat-resistant mutant IL62–3 (L*→HR). Alternatively, reactions contained only T1L ISVPs (L+L), T3D ISVPs (D+D), or IL62–3 ISVPs (HR+HR), without any preconverted particles. Reactions were incubated at the indicated temperature and then assayed for TRY sensitivity, and the δ remaining after TRY digestion was quantitated. For samples containing preconverted ISVPs, 50% protease-resistant δ indicates no promoting activity because the preconverted ISVPs and target ISVPs are present in equal parts. Each point represents the mean of two or three determinations.