Fig. 6. BMP4 stimulation induces Smad4/Smad5/CBP association and DNA-binding
activity in spermatogonia. (A) Eighty µg of total cell protein extracts
from control or BMP4-treated spermatogonia were immunoprecipitated for Smad4
(lower panel) and immunoblotted for Smad5 and CBP (upper and middle panel,
respectively). (B) DNA-binding activity in nuclear extracts from control and
BMP4-treated spermatogonia probed with a
3xGCCG-[
-32P]ATP double-stranded oligonucleotide, in
the presence of 100x molar excess of competitors (wild-type or mutated
3xGCCG double-stranded oligonucleotides) or in the presence of an
anti-Smad4 antibody. (C) DNA-binding activity in nuclear extracts from control
and BMP4-treated spermatogonia probed with a
3xGCCG-[
-32P]ATP double-stranded oligonucleotide, in
the presence or absence of anti-Smad5 and anti-Smad8 antibodies.