Figure 7.

PKA phosphorylation of A-, B- and c-Myb DBDs. Recombinant NR₁₂₃ and R₂R₃ domains for A-, B- and c-Myb were phosphorylated in vitro with [γ-³²P]ATP and purified bovine PKA Cα catalytic subunit for 15 min before addition of SDS buffer, separation on a 15% SDS–polyacrylamide gel and autoradiography (as described in Materials and Methods). Top, Coomassie-stained gel; bottom, corresponding autoradiogram. N, phosphorylation reaction c-Myb R₂R₃ without PKA Cα added; C, B and A indicate c-, B- or A-Myb R₂R₃ or NR₁₂₃ domains, respectively, as indicated. Proteins, phosphoproteins and free [γ-³²P]ATP are marked with arrows.