The properties of the binding of recombinant rat nucleoside diphosphate (NDP) kinase isoforms a and β (NDP kinase α and β respectively) to bleached bovine retinal rod outer segment (ROS) membranes were investigated. It was found that: (1) both NDP kinase isoforms interacted with ROS membranes in a pH-, cation- and GTPγS-dependent manner; (2) the retinal G-protein transducin was an obligatory factor for the interaction; (3) the apparent affinity of NDP kinase a for ROS membranes was about 100-fold higher than that of NDP kinase β; and (4) an α-isoform-specific peptide, corresponding to the sequence of the N-terminal third (variable region), had the ability to displace bovine NDP kinase from ROS membranes. The results suggest the possible involvement of NDP kinases in cellular regulation via interaction with G-proteins and provide a structural basis for the possible differential roles of mammalian NDP kinase isoforms in the cell.
