Co-Authors:
Ishaaya, I., Research Institute, Canada Department of Agriculture, University Sub P.O., London, Ont., Canada
Chefurka, W., Research Institute, Canada Department of Agriculture, University Sub P.O., London, Ont., Canada
Abstract:
Sucrose density gradient centrifugation was used to fractionate the microsomes from the housefly Musca domestica into two components, the free ribosomes and the membranes. The effect of actinomycin D (AM) on the in vivo incorporation of leucine into these fractions was studied. Actinomycin D rapidly inhibited RNA synthesis which however, did not result in a rapid inhibition of incorporation of leucine into the free ribosomes. The half-decay time of this inhibition was about 5 h suggesting a relatively stable m RNA. Under identical conditions the incorporation of leucine into the proteins of the membranes was stimulated about two-fold within 2 h after treatment. This enhanced rate of incorporation could be maintained for at least 4 h by a subsequent injection of actinomycin otherwise it rapidly fell off to normal levels. Puromycin completely prevented this stimulation by actinomycin. It is suggested that this enhanced incorporation is due to de-repression of membrane activity as a result of preferential inhibition of synthesis of mRNA for the repressor protein. © 1971.