FIG. 5.

Mapping the region of GATA4 that interacts with myocardin. (A) Schematic diagrams of GATA4 mutants and their activities. (B) A GST-myocardin fusion protein encompassing amino acids 129 to 510 was incubated with [³⁵S]methionine-labeled GATA proteins translated in vitro. GATA4 proteins associated with GST-myocardin are shown at the top, and 10% of the input proteins are shown at the bottom. (C) COS cells were transiently transfected with the luciferase reporter plasmids shown above each panel and expression vectors encoding myocardin (100 ng) and GATA4 or GATA4 mutants (100 ng) shown in panel A, as indicated. Luciferase activity was assayed and is expressed as fold activation above the level of expression of the reporter alone. (D) Point mutants in Cf of GATA4 and their activities. (E) A GST-myocardin fusion protein encompassing amino acids 129 to 510 was incubated with [³⁵S]methionine-labeled GATA proteins translated in vitro. GATA4 proteins associated with GST-myocardin or GST are shown at the top and middle, respectively, and 10% of the input proteins are shown at the bottom. (F) COS cells were transiently transfected with the luciferase reporter plasmids shown above each panel and expression vectors encoding myocardin (100 ng) and GATA4 or GATA4 mutants (100 ng) shown in panel D, as indicated. Luciferase activity was assayed and is expressed as fold activation above the level of expression of the reporter alone.