The nucleoplasmic protein, Lamina-associated polypeptide (LAP) 2␣, is one of six alternatively spliced products of the LAP2gene, which share a common N-terminal region. In contrast to the other isoforms, which also share most of their C termini, LAP2␣ has a large unique C-terminal region that contains binding sites for chromatin, A-type lamins, and retinoblastoma protein. By immunoprecipitation analyses of LAP2␣ complexes from cells expressing differently tagged LAP2␣ proteins and fragments, we

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... demonstrate that LAP2␣ forms higher order structures containing multiple LAP2␣ molecules in vivo and that complex formation is mediated by the C terminus. Solid phase binding assays using recombinant and in vitro translated LAP2␣ fragments showed direct interactions of LAP2␣ C termini. Cross-linking of LAP2␣ complexes and multiangle light scattering of purified LAP2␣ revealed the existence of stable homo-trimers in vivo and in vitro. Finally, we show that, in contrast to the LAP2␣-lamin A interaction, its self-association is not affected by a disease-linked single point mutation in the LAP2␣ C terminus.