Fig. 5. Effect of ATP binding and kinase and activity on the regulated subcellular distribution of p94fer and p51ferT. A, fer G571R (a), fer G576V (b), fer D685E (c) and fer Y715F (d), all linked to a HA epitope were transiently expressed in actively growing COS1 cells. Cells were than fixed and stained with -HA monoclonal antibody. Photographs represent stacked confocal sections. Scale bar, 20 µm. B, schematic summary of the p94fer (fer) and p51ferT (ferT) constructs, which were tested in growth-arrested confluent (conf.) and nonconfluent (nonconf.) COS1 cells. The different mutants are listed (kinase), and the mutated sites are described in parentheses. (ATP s.), mutation in ATP binding site; (cat. s.), mutation in a catalytic residue; (phos. s.), mutation in an autophosphorylation site. The expected effects on enzymatic functions are described. ATP b., binding of ATP: -, abolished; +/-, impaired; +, normal binding. Cat A., autophosphorylation activity: -, loss of catalytic activity; +/-, impaired; +, normal autophosphorylation activity; n.d., not determined. Signs that describe the nuclear accumulation of the various mutants are as in Fig. 3B
, and the values were determined according to the described procedure.