title: Intracellular localization of porcine single-strand binding protein 2.
abstract: We have previously cloned cofactor CLIM2 (Ldb1/NL1) as a binding protein for LIM homeodomain transcription factor and now seek a protein interacting with CLIM2. Ultimately, SSBP2 was cloned as CLIM2 binding protein from the adult porcine pituitary cDNA library by the Yeast Two-Hybrid System. The amino acid sequence of porcine SSBP2 shows a high identity (99%) with those of other mammalian species, man, and mouse. Using fluorescence protein-fused SSBP2 and its deletion mutants, we observed that SSBP2 overexpressed in CHO cells predominantly localizes in mitochondria. Expression of mutant SSBP2s demonstrated that the first 241 amino acid residues are responsive for the mitochondrial localization. When CLIM2 vector was co-transfected, SSBP2 changed its location to nuclei. The similar translocation was also observed when CLIM2 vector was transfected 17 h after the transfection of SSBP2 vector. The first 120 residues of SSBP2 are responsible for the nuclear localization by guidance with CLIM2. RT-PCR demonstrated that SSBP2 was expressed in the porcine pituitary from fetal 40 days to postnatal 230 days in both genders and in the variety of pituitary and non-pituitary tumor cell lines, indicating that SSBP2 is present ubiquitously and plays a universal function during fetal and postnatal pituitary development.
authors.affiliation: Division of Life Science, Graduate School of Agriculture, Meiji University, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan. yukato@isc.meiji.ac.jp
authors.forename: Yukio
authors.initials: Y
authors.lastname: Kato
authors.forename: Takako
authors.initials: T
authors.lastname: Kato
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Ono
authors.forename: Takao
authors.initials: T
authors.lastname: Susa
authors.forename: Kousuke
authors.initials: K
authors.lastname: Kitahara
authors.forename: Kaori
authors.initials: K
authors.lastname: Matsumoto
mesh_terms: D021581:Active Transport, Cell Nucleus; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D004268:DNA-Binding Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D008928:Mitochondria / Q000737:chemistry; D009154:Mutation; D010902:Pituitary Gland / Q000196:embryology / Q000254:growth & development; D013552:Swine; D014157:Transcription Factors / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D014162:Transfection
chemical_list: D004268:DNA-Binding Proteins; D014157:Transcription Factors