Lamina-associated polypeptide 2alpha binds intranuclear A-type lamins.
The nucleoskeletal protein lamina-associated polypeptide 2(&agr;) (LAP2*) contains a large, unique C terminus and differs significantly from its alternatively spliced, mostly membrane-integrated isoforms, such as LAP2beta. Unlike lamin B-binding LAP2beta, LAP2alpha was found by confocal immunofluorescence microscopy to colocalize preferentially with A-type lamins in the newly formed nuclei assembled after mitosis. While only a subfraction of lamins A and C (lamin A/C) was associated with the predominantly nuclear LAP2alpha in telophase, the majority of lamin A/C colocalized with LAP2alpha in G(1)-phase nuclei. Furthermore, selective disruption of A-type lamin structures by overexpression of lamin mutants in HeLa cells caused a redistribution of LAP2alpha. Coimmunoprecipitation experiments revealed that a fraction of lamin A/C formed a stable, SDS-resistant complex with LAP2alpha in interphase cells and in postmetaphase cell extracts. Blot overlay binding studies revealed a direct binding of LAP2alpha to exclusively A-type lamins and located the interaction domains to the C-terminal 78 amino acids of LAP2alpha and to residues 319-566 in lamin A/C, which include the C terminus of the rod and the entire tail common to lamin A/C. These findings suggest that LAP2alpha and A-type lamins cooperate in the organization of internal nuclear structures.
Dechat
T
T
Department of Biochemistry and Molecular Cell Biology, Vienna Biocenter, University of Vienna, A-1030 Vienna, Austria.
Korbei
B
B
Vaughan
O A
OA
Vlcek
S
S
Hutchison
C J
CJ
Foisner
R
R
D020816:Amino Acid Motifs; D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D002467:Cell Nucleus / Q000737:chemistry / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins; D005456:Fluorescent Dyes; D006367:HeLa Cells; D022781:Hepatocytes / Q000166:cytology; D006801:Humans; D007399:Interphase; D034904:Lamin Type A; D034921:Lamin Type B; D034882:Lamins; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008938:Mitosis; D015739:Nocodazole / Q000494:pharmacology; D009687:Nuclear Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D051381:Rats; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
D004268:DNA-Binding Proteins; D005456:Fluorescent Dyes; D034904:Lamin Type A; D034921:Lamin Type B; D034882:Lamins; D008565:Membrane Proteins; D009687:Nuclear Proteins; D010446:Peptide Fragments; D011994:Recombinant Proteins; C093413:lamina-associated polypeptide 2; D004247:DNA; D015739:Nocodazole