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Mol. Cell. Biol., 05 1995, 2448-2456, Vol 15, No. 5
M Crossley, M Merika and SH Orkin
GATA-1, the founding member of a distinctive family of transcription
factors, is expressed predominantly in erythroid cells and participates in
the expression of numerous erythroid cell-expressed genes. GATA- binding
sites are found in the promoters and enhancers of globin and nonglobin
erythroid genes as well as in the alpha- and beta-globin locus control
regions. To elucidate how GATA-1 may function in a variety of regulatory
contexts, we have examined its protein-protein interactions. Here we show
that GATA-1 self-associates in solution and in whole-cell extracts and that
the zinc finger region of the molecule is sufficient to mediate this
interaction. This physical interaction can influence transcription, as
GATA-1 self-association is able to recruit a transcriptionally active but
DNA-binding-defective derivative of GATA-1 to promoter-bound GATA-1 and
result in superactivation. Through in vitro studies with bacterially
expressed glutathione S- transferase fusion proteins, we have localized the
minimal domain required for GATA-1 self-association to 40 amino acid
residues within the C-terminal zinc finger region. Finally, we have
detected physical interaction of GATA-1 with other GATA family members
(GATA-2 and GATA- 3) also mediated through the zinc finger domain. These
findings have broad implications for the involvement of GATA factors in
transcriptional control. In particular, the interaction of GATA-1 with
itself and with other transcription factors may facilitate its function at
diverse promoters in erythroid cells and also serve to bring together, or
stabilize, loops between distant regulatory elements, such as the globin
locus control regions and downstream globin promoters.(ABSTRACT TRUNCATED
AT 250 WORDS)
Copyright © 1995, American Society for Microbiology
Self-association of the erythroid transcription factor GATA-1 mediated by its zinc finger domains
Division of Hematology-Oncology, Children's Hospital, Boston, Massachusetts 02115, USA.
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