title: The N-terminal sequence directs import of mitochondrial alanine aminotransferase into mitochondria.
abstract: Herein, we report cloning and subcellular localization of two alanine aminotransferase (ALT) isozymes, cALT and mALT, from liver of gilthead sea bream (Sparus aurata). CHO cells transfected with constructs expressing cALT or mALT as C- or N-terminal fusion with the enhanced green fluorescent protein (EGFP) showed that cALT is cytosolic, whereas mALT localized to mitochondria. Fusion of EGFP to mALT N-terminus or removal of amino acids 1-83 of mALT avoided import into mitochondria, supporting evidence that the mALT N-terminus contains a mitochondrial targeting signal. The amino acid sequence of mALT is the first reported for a mitochondrial ALT in animals.
authors.affiliation: Departament de Bioquímica i Biologia Molecular, Facultat de Farmàcia, Universitat de Barcelona, Diagonal 643, 08028 Barcelona, Spain.
authors.forename: Isidoro
authors.initials: I
authors.lastname: Metón
authors.forename: Miriam
authors.initials: M
authors.lastname: Egea
authors.forename: Felipe
authors.initials: F
authors.lastname: Fernández
authors.forename: María C
authors.initials: MC
authors.lastname: Eraso
authors.forename: Isabel V
authors.initials: IV
authors.lastname: Baanante
mesh_terms: D000410:Alanine Transaminase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001483:Base Sequence; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D049452:Green Fluorescent Proteins; D007527:Isoenzymes; D008164:Luminescent Proteins / Q000235:genetics; D008930:Mitochondria, Liver / Q000201:enzymology*; D008969:Molecular Sequence Data; D009711:Nucleotides / Q000235:genetics; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D021541:Sea Bream; D013347:Subcellular Fractions / Q000201:enzymology; D014162:Transfection
chemical_list: D007527:Isoenzymes; D008164:Luminescent Proteins; D009711:Nucleotides; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D000410:Alanine Transaminase