Translational Initiation of Ornithine Decarboxylase mRNA
The polyamines (putrescine, spermidine and spermine) are a group of small intracellular aliphatic amines essential for a variety of growth-related processes in the cell. The importance of the polyamines in cell function is reflected in a strict regulatory control of their intracellular levels. High polyamine concentration can be toxic to the cell, whereas low concentrations may negatively affect anabolic events such as the synthesis of DNA, RNA and protein, eventually giving rise to cell growth arrest. Ornithine decarboxylase (ODC) catalyzes the first and what is often considered as the rate-limiting step in the biosynthesis of the polyamines. The enzyme is highly regulated at a multitude of levels, including the translational level. Some of the mechanisms involved in the regulation of ODC are unique and resembling those found in the control of various protooncogenes. Due to the extremely fast turnover of ODC (half-life of minutes to an hour), the cellular level of ODC protein and thus the enzyme activity is rapidly altered when the synthesis and/or degradation of the enzyme is changed.
KeywordsOrnithine Decarboxylase Hypotonic Shock Ribosomal Frameshifting Strong Secondary Structure Ornithine Decarboxylase Antizyme
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