title: Establishment of a Cre/loxP recombination system for N-terminal epitope tagging of genes in Tetrahymena.
abstract: BACKGROUND
  Epitope tagging is a powerful strategy to study the function of proteins. Although tools for C-terminal protein tagging in the ciliated protozoan Tetrahymena thermophila have been developed, N-terminal protein tagging in this organism is still technically demanding.
  
  
  RESULTS
  In this study, we have established a Cre/loxP recombination system in Tetrahymena and have applied this system for the N-terminal epitope tagging of Tetrahymena genes. Cre can be expressed in Tetrahymena and localizes to the macronucleus where it induces precise recombination at two loxP sequences in direct orientation in the Tetrahymena macronuclear chromosome. This Cre/loxP recombination can be used to remove a loxP-flanked drug-resistance marker from an N-terminal tagging construct after it is integrated into the macronucleus.
  
  
  CONCLUSIONS
  The system established in this study allows us to express an N-terminal epitope tagged gene from its own endogenous promoter in Tetrahymena.
authors.affiliation: Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Dr Bohr-Gasse 3, A-1030 Vienna, Austria.
authors.forename: Clara Jana-Lui
authors.initials: CJ
authors.lastname: Busch
authors.forename: Alexander
authors.initials: A
authors.lastname: Vogt
authors.forename: Kazufumi
authors.initials: K
authors.lastname: Mochizuki
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001435:Bacteriophages / Q000201:enzymology; D001483:Base Sequence; D000939:Epitopes / Q000235:genetics / Q000378:metabolism; D005821:Genetic Techniques; D005822:Genetic Vectors / Q000235:genetics / Q000378:metabolism; D019426:Integrases / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011995:Recombination, Genetic; D013768:Tetrahymena / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D000939:Epitopes; D015800:Protozoan Proteins; D014764:Viral Proteins; C045073:Cre recombinase; D019426:Integrases