Papain digestion of CYT-19 and Δ578–626. A, Complete time course of digestion. Lane 1, undigested CYT-19; lanes 2–7, time course of CYT-19 digestion by papain. Lane 8, undigested Δ578–626; lanes 9–14, time course of Δ578–626 digestion by papain under the same conditions. Digestion times for each protein are: lanes 2 and 9, two min; lanes 3 and 10, six min; lanes 4 and 11, 15 min; lanes 5 and 12, 45 min; lanes 6 and 13, 60 min; lanes 7 and 14, 120 min. B, Early times of papain digestion. Lanes 1 and 8 show the undigested CYT-19 and Δ578–626 proteins, respectively. Other lanes show digestion times of: 30 s (lanes 2 and 9), 1 min 30 s (lanes 3 and 10), 2 min 30 s (lanes 4 and 11), 6 min (lanes 5 and 12), 8 min 30 s (lanes 6 and 13), and 20 min (lanes 7 and 14).