T. Nomura et al., NEGATIVE AUTOREGULATION OF C-MYB ACTIVITY BY HOMODIMER FORMATION THROUGH THE LEUCINE-ZIPPER, The Journal of biological chemistry, 268(29), 1993, pp. 21914-21923
The trans-activating and transforming capacities of the c-myb proto-on
cogene product (c-Myb) are negatively regulated through a leucine zipp
er structure in its negative regulatory domain. We show here that in c
ontransfection assays, maximal Myb-induced trans-activation occurs wit
h relatively low amounts of wild-type c-Myb, while higher levels of c-
Myb result in reduced Myb-induced trans-activation. By contrast, this
apparent negative autoregulation is not observed with a c-Myb mutant c
ontaining an impaired leucine zipper. Data presented here suggest that
this negative autoregulation of trans-activation by wild-type c-Myb i
s a consequence of homodimer formation by c-Myb through its leucine zi
pper and of the inability of c-Myb dimers to bind DNA. These findings
point to a novel mechanism of regulation of a transcription factor.