Ornithine decarboxylase; Catalyzes the first and rate-limiting step of polyamine biosynthesis that converts ornithine into putrescine, which is the precursor for the polyamines, spermidine and spermine. Polyamines are essential for cell proliferation and are implicated in cellular processes, ranging from DNA replication to apoptosis. Belongs to the Orn/Lys/Arg decarboxylase class-II family.

Antizyme inhibitor 2; Antizyme inhibitor (AZI) protein that positively regulates ornithine decarboxylase (ODC) activity and polyamine uptake. AZI is an enzymatically inactive ODC homolog that counteracts the negative effect of ODC antizymes (AZs) OAZ1, OAZ2 and OAZ3 on ODC activity by competing with ODC for antizyme-binding. Inhibits antizyme- dependent ODC degradation and releases ODC monomers from their inactive complex with antizymes, leading to formation of the catalytically active ODC homodimer and restoring polyamine production. Participates in the morphological integrity of the [...]

Ornithine decarboxylase antizyme 3; Ornithine decarboxylase (ODC) antizyme protein that negatively regulates ODC activity and intracellular polyamine biosynthesis and uptake in response to increased intracellular polyamine levels. Binds to ODC monomers, inhibiting the assembly of the functional ODC homodimers. Does not target the ODC monomers for degradation, which allows a protein synthesis-independent restoration of ODC activity. Stabilizes AZIN2 by interfering with its ubiquitination. Involved in the translocation of AZNI2 from ER- Golgi intermediate compartment (ERGIC) to the cytos [...]

Spermine synthase; Catalyzes the production of spermine from spermidine and decarboxylated S-adenosylmethionine (dcSAM).

Spermine oxidase; Flavoenzyme which catalyzes the oxidation of spermine to spermidine. Can also use N(1)-acetylspermine and spermidine as substrates, with different affinity depending on the isoform (isozyme) and on the experimental conditions. Plays an important role in the regulation of polyamine intracellular concentration and has the potential to act as a determinant of cellular sensitivity to the antitumor polyamine analogs. May contribute to beta-alanine production via aldehyde dehydrogenase conversion of 3-amino-propanal; Belongs to the flavin monoamine oxidase family.

Ornithine decarboxylase antizyme 1; Ornithine decarboxylase (ODC) antizyme protein that negatively regulates ODC activity and intracellular polyamine biosynthesis and uptake in response to increased intracellular polyamine levels. Binds to ODC monomers, inhibiting the assembly of the functional ODC homodimer, and targets the monomers for ubiquitin- independent proteolytic destruction by the 26S proteasome. Triggers ODC degradation by inducing the exposure of a cryptic proteasome- interacting surface of ODC. Stabilizes AZIN2 by interfering with its ubiquitination. Also inhibits cellular [...]

Peroxisomal N(1)-acetyl-spermine/spermidine oxidase; Flavoenzyme which catalyzes the oxidation of N(1)- acetylspermine to spermidine and is thus involved in the polyamine back-conversion. Can also oxidize N(1)- acetylspermidine to putrescine. Substrate specificity: N(1)- acetylspermine = N(1)-acetylspermidine > N(1),N(12)-diacylspermine >> spermine. Does not oxidize spermidine. Plays an important role in the regulation of polyamine intracellular concentration and has the potential to act as a determinant of cellular sensitivity to the antitumor polyamine analogs.

Spermidine synthase; Catalyzes the production of spermidine from putrescine and decarboxylated S-adenosylmethionine (dcSAM). Has a strong preference for putrescine as substrate, and has very low activity towards 1,3- diaminopropane. Has extremely low activity towards spermidine.