TRANSDUCIN-MEDIATED, ISOFORM-SPECIFIC INTERACTION OF RECOMBINANT RAT NUCLEOSIDE DIPHOSPHATE KINASES WITH BLEACHED BOVINE RETINAL ROD OUTER SEGMENT MEMBRANES

The properties of the binding of recombinant rat nucleoside diphosphat e (NDP) kinase isoforms alpha and beta (NDP kinase alpha and beta, res pectively) to bleached bovine retinal rod outer segment (ROS) membrane s were investigated, It was found that: (1) both NDP kinase isoforms i nteracted with ROS membranes in a pH-, cation- and GTP gamma S-depende nt manner; (2) the retinal G-protein transducin was an obligatory fact or for the interaction; (3) the apparent affinity of NDP kinase a for ROS membranes was about 100-fold higher than that of NDP kinase beta; and (4) an alpha-isoform-specific peptide, corresponding to the sequen ce of the N-terminal third (variable region), had the ability to displ ace bovine NDP kinase from ROS membranes, The results suggest the poss ible involvement of NDP kinases in cellular regulation via interaction nifh G-proteins and provide a structural basis for the possible diffe rential roles of mammalian NDP kinase isoforms in the cell.