Deletion of the C-terminal DAD motifs reduces FRL3.FH2 activity in
vivo. A, as in Fig.
1, expression of FRL3.FH2 induces thick stress fibers, actin
aggregates, and peripheral F-actin accumulation (98%, n = 101).
B, FRL3.FH2.1045 behaves similarly to FH2 (83%, n = 100).
C, FRL3.FH2.1023 induces thick stress fibers (75%, n = 102)
but no actin aggregates or peripheral F-actin. D, deletion of the
distal and proximal DAD motifs reduces the ability of FRL3.FH2 to induce
activation of an SRF reporter gene. Inset, relative levels of
expression of FRL3.FH2, FRL3.FH2.1045, and FRL3.FH2.1023 as determined by
immunoblotting. Reporter gene activity was standardized to activation induced
by expression of an SRF-VP16 control fusion protein. Error bars,
S.E., n = 3. E, schematic of FRL3.FH2 derivatives.