Nonerythroid alpha-spectrin (alphaSpIISigma( *)) is a structural protein that has been identified in the nucleus of mammalian cells and shown to be involved in DNA repair. It is also deficient in cells from the clinically diverse genetic disorder Fanconi anemia (FA). In order to get a clearer understanding of the role of alphaSpIISigma( *) in DNA repair, and whether it may have other important functions in the nucleus, studies were undertaken to identify specific alphaSpIISigma( *) protein binding partners in the nucleus. The results demonstrate that multiple proteins co-immunoprecipitate with alphaSpIISigma( *) from nuclear extracts from normal human lymphoblastoid and HeLa cells. These can be grouped into five categories: structural proteins, proteins involved in DNA repair, chromatin remodeling proteins, FA proteins, and transcription and RNA processing factors. These studies indicate that alphaSpIISigma( *) may play a role in a number of diverse and important processes in the nucleus and that a deficiency in this protein, as occurs in FA, could affect a number of critical cellular pathways.