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Mol. Cell. Biol., 03 1995, 1353-1363, Vol 15, No. 3
HY Yang and T Evans
We used a one-hybrid system to replace precisely the finger II chicken
GATA-1 DNA-binding domain with the binding domain of bacterial repressor
protein LexA. The LexA DNA-binding domain lacks amino acids that function
for transcriptional activation, nuclear localization, or protein
dimerization. This allowed us to analyze activities of GATA-1 sequences
distinct from DNA binding. We found that strong transcriptional activating
sequences that function independently of finger II are present in GATA-1.
Sequences including finger I contain an independent nuclear localizing
function. Our data are consistent with cooperative binding of two
LexA-GATA-1 hybrid proteins on a palindromic operator. The sensitivity of
our transcription assay provides the first evidence that GATA-1 can make
homotypic interactions in vivo. The ability of a non-DNA-binding form of
GATA-1 to activate gene expression by targeting to a bound GATA-1
derivative further supports the notion that GATA-1-GATA-1 interactions may
have functional consequences. A coimmunoprecipitation assay was used to
demonstrate that GATA-1 multimeric complexes form in solution by
protein-protein interaction. The novel ability of GATA-1 to interact
homotypically may be important for the formation of higher-order structures
among distant regulatory elements that share binding sites for this
transcription factor. We also used the system to test the ability of GATA-1
to interact heterotypically with other activators.
Copyright © 1995, American Society for Microbiology
Homotypic interactions of chicken GATA-1 can mediate transcriptional activation
Department of Biological Sciences, University of Pittsburgh, Pennsylvania 15260.
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