S. Maheswaran et al., INTRACELLULAR ASSOCIATION OF THE PROTEIN PRODUCT OF THE ONCOGENE WITHTHE TATA-BINDING PROTEIN, Molecular and cellular biology, 14(2), 1994, pp. 1147-1152
The c-myc proto-oncogene encodes nuclear phosphoproteins that bind DNA
in a sequence-specific fashion and appear to function as transcriptio
nal activators. Here we demonstrate that a 40-kDa nuclear protein coim
munoprecipitated with c-Myc specifically when nuclear proteins, extrac
ted from nuclei of exponentially growing murine B-lymphoma WEHI 231 ce
lls by using procedures for preparation of trans-acting factors, were
reacted with anti-c-Myc antibodies made against different regions of t
he c-Myc protein. In contrast, preparation of nuclear lysates under de
naturing conditions significantly reduced this coprecipitation. Upon i
ncubation of WEHI 231 cells with the reversible chemical cross-linking
agent dithiobis(succinimidyl propionate), the 40-kDa protein could be
cross-linked to c-Myc protein intracellularly. Identification of the
40-kDa protein as the TATA-binding protein (TBP) of the TFIID transcri
ption initiation complex was made by comigration and V-8 protease mapp
ing, which yielding identical peptide fragments upon digestion of the
40-kDa protein and material immunoprecipitated with an anti-TBP specif
ic antibody. Furthermore, in vitro-translated TBP bound to the amino-t
erminal portion of c-Myc. Column chromatography of cross-linked nuclea
r proteins showed TBP to be in a large-molecular-weight complex with c
-Myc, consistent with a transcription initiation complex. These result
s indicate that intracellularly, c-Myc interacts with TBP, suggesting
a mechanism of interaction of this oncoprotein with the basal transcri
ption machinery.