Cytoplasmic induction

Uric acid Cytoplasm Induction of DC maturation, inflammatory effect on macrophages... 

The alternative type of explanation is that the translation of these mENAs is specifically repressed by some mechanism (pres mably through the binding of the mENP proteins) and that their translation requires some sort of cytoplasmic induction. In this case, mobilisation of the mENA into polysomes would not necessarily follow treatment of the cells with low levels of cycloheximide, but would require exposure of the cells to the appropriate inducer. One possible candidate for an inducer may be Fe++ which causes a doubling in the rate of ferritin synthesis in tissue culture cells and in liver (64 65). In the control sitiiation only 50% of the cytoplasmic ferritin mENA in liver is associated with polysomes, and the rest occiirs as free mENPs. Administration of Fe" results in the rapid assimilation of all the ferritin mENA into polysomes (65). If further investigation confirms these results, and shows that Fe selectively controls ferritin mENA translation and has little effect... 

PNMT catalyzes the N-methylation of norepinephrine to form epinephrine in the epinephrine-forming cells of the adrenal medulla. Since PNMT is soluble, it is assumed that norepinephrine-to-epinephrine conversion occurs in the cytoplasm. The synthesis of PNMT is induced by glucocorticoid hormones that reach the medulla via the intra-adrenal portal system. This special system provides for a 100-fold steroid concentration gradient over systemic arterial blood, and this high intra-adrenal concentration appears to be necessary for the induction of PNMT. 

This ability to grow in polluted soils and withstand high heavy metal concentrations rests on complex mechanisms involving both avoidance through exclusion of metal ions from the cytoplasm and tolerance of high internal metal concentrations (126), this being often dependent on the induction of specific genes and proteins (126,127). 

Lohka MJ, Hayes MK, Mailer JL 1988 Purification of maturation-promoting factor, an intracellular regulator of early mitotic events. Proc Natl Acad Sci USA 85 3009—3013 Mailer JL, Butcher FR, Krebs EG 1979 Early effects of progesterone on levels of cyclic adenosine 3 5 -monophosphate in Xenopus oocytes. J Biol Chem 254 579-582 Masui Y 1967 Relative roles of the pituitary, follicle cells, and progesterone in the induction of oocyte maturation in Ranapipiens. J Exp Zool 166 365-375 Masui Y, Markert CL 1971 Cytoplasmic control of nuclear behavior during meiotic maturation of frog oocytes. J Exp Zool 177 129-145... 

In mammalian cells, previous reports proved the localization of proteasomes both in the cytoplasm and in the nucleus (Palmer et al. 1996 Peters et al. 1994). In a more recent study GFP-tagged 20 S proteasomes in fibrosarcoma cells were shown to be dispersed over the cytoplasm and nucleoplasm wherein they seem to diffuse rapidly (Reits et al. 1997). Reits et al. used a fusion protein of GFP with the proteasome subunit LMP2, ich replaces a p subimit of the proteasome upon induction with interferon y, a stimulator of... 

---