title: A compound C-terminal nuclear localization signal of human SA2 stromalin.
abstract: Stromalins are evolutionarily conserved multifunctional proteins with the best known function in sister chromatid cohesion. Human SA2 stromalin, likely involved in the establishment of cohesion, contains numerous potential nuclear localization (NLS) and nuclear export signals (NES). Previously we have found that the C-terminus of SA2 contains NLS(s) functional in human cells. However, the identity of this signal remained unclear since three NLS-like sequences are present in that region. Here we analyzed the functionality of these putative signals by expressing GFP-tagged C-terminal part of SA2 or its fragments in a human cell line and in the yeast Saccharomyces cerevisiae. We found that in human cells the nuclear import is dependent on a unique compound di- or tripartite signal containing unusually long linkers between clusters of basic amino acids. Upon expression of the same SA2 fragment in yeast this signal is also functional and can be easily studied in more detail.
authors.affiliation: Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland.
authors.forename: Leszek J
authors.initials: LJ
authors.lastname: Tarnowski
authors.affiliation: Department of Medical Genetics, Institute of Mother and Child, Warsaw, Poland.
authors.forename: Michal
authors.initials: M
authors.lastname: Milewski
authors.affiliation: Institute of Biochemistry, Faculty of Biology, University of Warsaw, Warsaw, Poland.
authors.forename: Jan
authors.initials: J
authors.lastname: Fronk
authors.affiliation: Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Kurlandzka
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D034961:Antigens, Nuclear / Q000378:metabolism*; D018797:Cell Cycle Proteins; D002467:Cell Nucleus / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D028884:Karyopherins / Q000378:metabolism; D008969:Molecular Sequence Data; D019913:Nuclear Localization Signals; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D000097606:Exportin 1 Protein; D000097722:Cohesins
chemical_list: D034961:Antigens, Nuclear; D018797:Cell Cycle Proteins; D049452:Green Fluorescent Proteins; D028884:Karyopherins; D019913:Nuclear Localization Signals; D018160:Receptors, Cytoplasmic and Nuclear; D011993:Recombinant Fusion Proteins; D000097606:Exportin 1 Protein; C508565:STAG2 protein, human; D000097722:Cohesins