A point mutation in the ATP-binding domain of UAP56 inhibits ATP binding. A point mutation in the ATP-binding domain of UAP56 inhibits ATP binding. A Lysine 95 to Asparagine mutation in the ATP-binding domain of GST-UAP56 was made. Using a method applied to previous DEAD-box helicases (Pause and Sonenberg, 1992), GST-UAP56 wt or GST-UAP56 K95N was UV-cross-linked to bound α-P32-ATP in the presence or absence of 0.1 OD260 units of polyU. The bound and unbound α-P32-ATP were separated on a 12% SDS-PAGE gel before phosphoimaging. The binding of α-P32-ATP was strongly reduced by the mutation but unaffected by polyU. Krishna P. Kota et al. J Cell Sci 2008;121:1526-1537 © The Company of Biologists Limited 2008