Lamina-associated polypeptide 2α forms complexes with heat shock proteins Hsp70 and Hsc70 in vivo

Lamina-associated polypeptide 2alpha (LAP2alpha), one of the alternatively spliced isoforms of the LAP2 gene, is a nucleoplasmic protein which forms oligomers and presumably associates to chromosomes via the LEM- and LEM-like regions. To characterize components of the LAP2alpha-containing complexes, we have expressed the alpha-specific C-terminal domain of LAP2alpha in HeLa cells and, after immunopurification, found that the heat shock proteins Hsp70 and Hsc70 reproducibly co-purified with this domain. Association between endogenous LAP2alpha and Hsp70 in non-transfected cells was confirmed by co-immunoprecipitation. The association was not mediated by the retinoblastoma protein.