224 



TORE HULTIN et al. 



Irrespective of whether [^"^CJ-L-leucine or [^^C]-L-lysine was used as labelled 

 component in the system, a considerably reduced incorporation activity 

 was observed with the microsomes from the phalloidin-treated animals. 



That this effect on the activity of the microsomes was mediated in 

 some way by the membrane components was suggested by the fact that 

 isolated RNP-particles from the same animals showed no significant 



mg of microsomal protein 



Fig. 2. Incorporation activity of liver microsomes from normal and phalloidin- 

 treated guinea-pigs. Incorporation system as in Fig. i, with 9 mg. of soluble 

 proteins from normal liver. Incubation period 15 min. (35 ). After the addition 

 of TCA the tubes were adjusted to equal protein contents [5]. Upper curves: 

 normal microsomes. Lozver curves: microsomes from phalloidin-treated animals 

 (o'5 /^g-/kg, 2 hr.). Solid curves :[^'^C]-i.-\eucine (o-o8 /xmole, 5-75 mC/mmole). 

 Broken curves: ['^]C-L-lysine (0-04 /imole, 13 "5 mC/mmole). 



inhibition under these conditions (Table I). Not until later, when the 

 phalloidin-effect had become more manifest (or under the influence of a 

 higher phalloidin concentration) did the isolated particles give evidence of 

 irreversible damage, as indicated by the incorporation data. The RNA/ 

 protein ratio of the microsomes was not influenced by the early phalloidin- 

 effects described here. 



In this connection it should be noted that in the early stages of the 

 phalloidin treatment no impairment could be demonstrated of a number 



