Fig. 6. Binding of site-directed mutants of A.aeolicus Trbp111 to . Gel mobility shift assays of mutant proteins binding to 5′-[³²P] are listed schematically according to the location of the mutation along the polypeptide sequence. In each assay the top band of the gel corresponds to protein-bound . The boxes mark concentrations of Trbp111 at which complex formation is half-maximal. The corresponding sites of the mutations and binding affinities relative to the wild-type protein are listed on the right. Arrows indicate mutants with decreased or diminished tRNA binding.