RNA synthesis in intact rat liver nuclei

Spermidine stimulation of foot-and-mouth disease virus RNA-dependent RNA polymerase activity

“…This synergistic effect would not appear to be due to neutralizing the inhibitory effect of newly synthesized I~NA chains nor its deplacement (1,4,5,8) from the RNA template since no substantial increase over the maximized conditions for enzyme activity have been observed in this system. That similar augmentation of activity was reported with more purified polymerase preparations (1,4,5,7,8), these results could be interpreted as a utilization of a polyamine as a polyfunctionM cation (9) in the cationic requirement for enzyme activity. This effect depends upon and mediated by a low concentration of Mg~+: Once maximum conditions are reached, further stimulation ceases irrespective of the strandedness or configuration of the template upon which I~NA is synthesized (4,6,23).…”

“…Polyamines stimulate the in vitro synthesis of RNA by DNA-dependent RNA polymerases (1--9) as well as polypeptides (10--14) from both bacterial (1--8, 11--14) and mammalian (7,9,10) sources. The mode of action during t~NA replication appears to be associated with the binding of polyamines to nascent RNA chains (15) thereby neutralizing product inhibition (1,2,4,5,8).…”

Polyamines and their biosynthetic decarboxylases in various tissues of the young rat during recovery from undernutrition

“…The polyamines have been shown to exert effects on transcription (Singh & Sung, 1972;Moruzi et al, 1974;Caldarera et al, 1975), translation (Moruzzi et al, 1968;Giorgi, 1970;Konecki et al, 1975) and the methylation and aminoacylation of tRNA (Leboy, 1970;Aoyama & Chaimovich, 1973). In addition the polyamines bind to and stabilize the cell organelles involved in these processes: the nucleus (Busch et al, 1967;MacGregor & Mahler, 1967), nucleolus (Gfeller et al, 1972), ribosomes, polyribosomes and microsomal fraction (Siekevitz & Palade, 1962;Khawaja, 1971).…”