Regulation of ornithine decarboxylase (ODC)

Polyamines increase the production of antizyme (AZ). The carboxy-terminal half of antizyme interacts with ODC, generating an inactive AZ:ODC heterodimer complex. A carboxy-terminal domain of ODC is exposed only within the heterodimer, and is the target for subsequent degradation. A domain within the amino-terminal portion of antizyme provides a function needed for efficient degradation of ODC by the proteasome. <br>The proteasome cycle starts with the processing of AZ:ODC, sequestering ODC and then degrading it to peptides but releasing AZ. AZ participates in additional rounds of binding and degradation. Antizyme-mediated inhibition and destruction of ODC reduces synthesis of polyamines. Additionally, antizyme also inhibits polyamine transport into the cell. Antizyme production is reduced, completing the regulatory circuit (Coffino, 2001).<br>The following illustration is adapted from a minireview by Pegg, 2006; J. Biol. Chem., Vol. 281, Issue 21, 14529-14532.

多胺促进抗锌酶（AZ）的生成。抗锌酶的羧基末端部分与ODC相互作用，形成一种非活性AZ:ODC异源二聚体复合物。ODC的羧基末端结构域仅在异源二聚体中暴露，并成为后续降解的目标。抗锌酶氨基末端部分内的结构域为蛋白体高效降解ODC提供所需功能。蛋白体循环始于AZ:ODC的处理，隔离ODC然后将其降解为肽段，但释放AZ。AZ参与额外的结合和降解循环。抗锌酶介导的ODC抑制和破坏减少多胺的合成。此外，抗锌酶还抑制多胺进入细胞。抗锌酶的生成减少，从而完成调控回路（Coffino，2001）。以下插图改编自Pegg于2006年发表的小综述；J. Biol. Chem., 第281卷，第21期，14529-14532页。