title: Functional diversity of LAP2alpha and LAP2beta in postmitotic chromosome association is caused by an alpha-specific nuclear targeting domain.
abstract: Lamina-associated polypeptide 2alpha (LAP2alpha) is a non-membrane-bound isoform of the LAP2 family implicated in nuclear structure organization. We show that during postmitotic nuclear assembly LAP2alpha associates with chromosomes prior to accumulation of the membrane-bound isoform LAP2beta, although both proteins contain the same putative chromatin interaction domains located in their common N-terminal regions. By transient and stable expression of various N- and C-terminal LAP2alpha deletion mutants in HeLa cells, we identified an approximately 350-amino-acid-long region in the C-terminal alpha-specific domain of the protein that is required for retention of LAP2alpha in interphase nuclei and for association with mitotic chromosomes, while the N-terminal domain seemed to be dispensable for these interactions. In vitro chromosome binding studies using recombinant LAP2alpha mutants revealed that this LAP2alpha-specific 'nuclear targeting domain' was essential and sufficient for association with chromosomes. These data suggested a functional diversity of chromosome binding properties of LAP2 isoforms.
authors.affiliation: Department of Biochemistry and Molecular Cell Biology, Biocenter, University of Vienna, Dr Bohrgasse 9, A-1030 Vienna, Austria.
authors.forename: S
authors.initials: S
authors.lastname: Vlcek
authors.forename: H
authors.initials: H
authors.lastname: Just
authors.forename: T
authors.initials: T
authors.lastname: Dechat
authors.forename: R
authors.initials: R
authors.lastname: Foisner
mesh_terms: D000818:Animals; D001665:Binding Sites; D016466:CHO Cells; D002453:Cell Cycle / Q000502:physiology*; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D002875:Chromosomes / Q000378:metabolism*; D006224:Cricetinae; D004268:DNA-Binding Proteins; D006367:HeLa Cells; D006801:Humans; D007399:Interphase; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008677:Metaphase; D008938:Mitosis; D016296:Mutagenesis; D009687:Nuclear Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D017384:Sequence Deletion; D014162:Transfection
chemical_list: D004268:DNA-Binding Proteins; D008565:Membrane Proteins; D009687:Nuclear Proteins; D020033:Protein Isoforms; D011994:Recombinant Proteins; C093413:lamina-associated polypeptide 2