ABSTRACT
It is possible to state that the mechanisms involved in polyamine regulation probably emerged to avoid the accumulation or depletion to dangerous levels of intracellular polyamines, as well as to provide enough polyamine concentrations in time and space during the occurrence of specic processes such as cell proliferation and differentiation, as well as during stressful conditions where higher levels of polyamines are required. Accordingly, it is known that an excess of polyamines can be relieved through their sequestration within vacuoles or even through catabolization, since while polyamines are essential, at the same time, high levels may become cytotoxic. Other mechanisms for the regulation of polyamine concentration take place at the levels of transcription, translation, and posttranslation processes. The interplay of all these mechanisms secures that the levels of polyamines are tightly regulated by a quite complex mechanism, as discussed in this chapter.
