Working together to bind DNA. The specificity of DNA binding by
the ets protein GABPa is determined by
formation of a heterotetramer (a2-b2)
that recognizes a binding site with two 5¢-GGA-3¢
cores. In the a subunit, the ETS domain functions
in DNA binding, inhibitory sequences are proposed to negatively regulate
DNA binding, and the pointed (PNT) domain is a structural domain conserved
in some ETS domain proteins. In the b subunit,
the leucine zipper motif (LEU ZIPPER) mediates b-subunit
interaction, the transactivation domain is required for transcriptional
activation, and ankyrin repeats form the interface with the a
subunit. Flexibility in the linkage between the leucine zipper region and
ankyrin repeats of GABPb is proposed to accommodate
recognition of direct repeats of GGA (shown) or inverted repeats of the
GGA core with variable spacing. The asterisks indicate phosphate contacts
detected in the crystal structure.
ILLUSTRATION: K. SUTLIFF
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Copyright © 1998 by the American Association for the Advancement of Science.