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.
Mesh Terms:
Amino Acid Motifs, Animals, Blotting, Western, Cell Line, Cell Nucleus, DNA, DNA-Binding Proteins, Fluorescent Dyes, Hela Cells, Hepatocytes, Humans, Interphase, Lamin Type A, Lamin Type B, Lamins, Membrane Proteins, Microscopy, Confocal, Microscopy, Fluorescence, Mitosis, Nocodazole, Nuclear Proteins, Peptide Fragments, Precipitin Tests, Protein Binding, Rats, Recombinant Proteins
J. Cell. Sci.
Date: Oct. 01, 2000
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