Identification and characterization of an ataxin-1-interacting protein: A1Up, a ubiquitin-like nuclear protein.

Identifies an ataxin-1-interacting ubuiquitin-like protein (A1Up) using the yeast two-hybrid system. Presence of A1U mRNA in Purkinje cells; Role of ataxin-1 in the formation and regulation of multimeric protein complexes within the nucleus; Relationship between the co-localization of A1Up with ataxin-1 in transfected cells and the extent of A1Up expressed and the number of glutamines in ataxin-1.