title: Subcellular localization and phosphorylation of antizyme 2.
abstract: Antizymes (AZs) are polyamine-induced proteins that negatively regulate cellular polyamine synthesis and uptake. Three antizyme isoforms are conserved among mammals. AZ1 and AZ2 have a broad tissue distribution, while AZ3 is testis specific. Both AZ1 and AZ2 inhibit ornithine decarboxylase (ODC) activity by binding to ODC monomer and target it to the 26S proteasome at least in vivo. Both also inhibit extra-cellular polyamine uptake. Despite their being indistinguishable by these criteria, we show here using enhanced green fluorescent protein (EGFP)-AZ2 fusion protein that in mammalian cells, the subcellular location of AZ2 is mainly in the nucleus, and is different from that of AZ1. The C-terminal part of AZ2 is necessary for the nuclear distribution. Within a few hours, a shift in the distribution of EGFP-AZ2 fusion protein from cytoplasm to the nucleus or from nucleus to cytoplasm is observable in NIH3T3 cells. In addition, we found that in cells a majority of AZ2, but not AZ1, is phosphorylated at Ser-186, likely by protein kinase CK2. There may be a specific function of AZ2 in the nucleus.
authors.affiliation: Department of Molecular Biology, The Jikei University School of Medicine, 3-25-8 Nishi-shinbashi, Minato-ku, Tokyo 105-8461, Japan. nmurai@jikei.ac.jp
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Murai
authors.forename: Akihiro
authors.initials: A
authors.lastname: Shimizu
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Murakami
authors.forename: Senya
authors.initials: S
authors.lastname: Matsufuji
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002467:Cell Nucleus / Q000378:metabolism; D002522:Chlorocebus aethiops; D003593:Cytoplasm / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D010766:Phosphorylation; D011073:Polyamines / Q000737:chemistry*; D046988:Proteasome Endopeptidase Complex / Q000737:chemistry*; D020033:Protein Isoforms; D011506:Proteins / Q000737:chemistry / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
chemical_list: D011073:Polyamines; D020033:Protein Isoforms; D011506:Proteins; C031017:ornithine decarboxylase antizyme; D049452:Green Fluorescent Proteins; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease