title: Identification of the nuclear export signals that regulate the intracellular localization of the mouse CMP-sialic acid synthetase.
abstract: The CMP-sialic acid synthetase (CSS) catalyzes the activation of sialic acid (Sia) to CMP-Sia which is a donor substrate of sialyltransferases. The vertebrate CSSs are usually localized in nucleus due to the nuclear localization signal (NLS) on the molecule. In this study, we first point out that a small, but significant population of the mouse CMP-sialic acid synthetase (mCSS) is also present in cytoplasm, though mostly in nucleus. As a mechanism for the localization in cytoplasm, we first identified two nuclear export signals (NESs) in mCSS, based on the localization studies of the potential NES-deleted mCSS mutants as well as the potential NES-tagged eGFP proteins. These two NESs are conserved among mammalian and fish CSSs, but not present in the bacterial or insect CSS. These results suggest that the intracellular localization of vertebrate CSSs is regulated by not only the NLS, but also the NES sequences.
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Fujita
authors.forename: Chihiro
authors.initials: C
authors.lastname: Sato
authors.forename: Ken
authors.initials: K
authors.lastname: Kitajima
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002467:Cell Nucleus / Q000201:enzymology*; D051379:Mice; D008969:Molecular Sequence Data; D000216:N-Acylneuraminate Cytidylyltransferase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry; D010957:Plasmids; D011089:Polydeoxyribonucleotides / Q000737:chemistry; D016133:Polymerase Chain Reaction; D021381:Protein Transport; D011994:Recombinant Proteins / Q000378:metabolism; D017384:Sequence Deletion
chemical_list: D010446:Peptide Fragments; D011089:Polydeoxyribonucleotides; D011994:Recombinant Proteins; D000216:N-Acylneuraminate Cytidylyltransferase