Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
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Gene/Protein
Disease
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Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
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Enzyme
Compound
Query: EC:2.3.1.28 (
chloramphenicol acetyltransferase
)
5,100
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
ATBF1
is a 306-kDa protein containing four homeodomains, 17 zinc finger motifs, and several segments potentially involved in transcriptional regulation (T. Morinaga, H. Yasuda, T. Hashimoto, K. Higashio, and T. Tamaoki, Mol. Cell. Biol. 11:6041-6049, 1991). At least one of the homeodomains of
ATBF1
binds to an AT-rich element in the human alpha-fetoprotein (AFP) enhancer (enhancer AT motif). In the present work, we analyzed the transcriptional regulatory activity of
ATBF1
with respect to the enhancer AT motif and similar AT-rich elements in the human AFP promoter and the human albumin promoter and enhancer. Gel retardation assays showed that
ATBF1
binds to the AFP enhancer AT motif efficiently; however, it binds weakly or not at all to other AT-rich elements in the AFP and albumin regulatory regions studied. Alterations of the enhancer AT motif by site-specific mutagenesis resulted in the loss of binding of
ATBF1
. Cotransfection experiments with an
ATBF1
expression plasmid and the
chloramphenicol acetyltransferase
(
CAT
) gene fused to AFP promoter or enhancer fragments showed that
ATBF1
suppressed the activity of AFP enhancer and promoter regions containing AT-rich elements. This suppression was reduced when the mutated AT motifs with low affinity to
ATBF1
were linked to the
CAT
gene. The
ATBF1
suppression of AFP promoter and enhancer activities appeared to be due, at least in part, to competition between
ATBF1
and HNF1 for the same binding site. In contrast to the AFP promoter and enhancer, the albumin promoter and enhancer were not affected by
ATBF1
, although they contain homologous AT-rich elements. These results show that
ATBF1
is able to distinguish AFP and albumin AT-rich elements, leading to selective suppression of the AFP promoter and enhancer activities.
...
PMID:ATBF1, a multiple-homeodomain zinc finger protein, selectively down-regulates AT-rich elements of the human alpha-fetoprotein gene. 750 6
The human
ATBF1
cDNA reported previously, now termed ATBF1-B, encodes a 306-kDa protein containing 4 homeodomains and 18 zinc fingers including one pseudo zinc finger motif. Here, we report the isolation of a second
ATBF1
cDNA, 12 kilobase pairs long, termed
ATBF1-A
. The deduced
ATBF1-A
protein is 404 kDa in size and differs from ATBF1-B by a 920-amino acid extention at the N terminus. Analysis of 5'-genomic sequences showed that the 5'-noncoding sequences specific to
ATBF1-A
and ATBF1-B transcripts were contained in distinct exons that could splice to a downstream exon common to the
ATBF1-A
and ATBF1-B mRNAs. The expression of
ATBF1-A
transcripts increased to high levels when P19 and NT2/D1 cells were treated with retinoic acid to induce neuronal differentiation. Preferential expression of
ATBF1-A
transcripts was also observed in developing mouse brain. Transient transfection assays showed that the 5.5-kilobase pair sequence upstream of the
ATBF1-A
-specific exon (exon 2) supported expression of the linked
chloramphenicol acetyltransferase
gene in neuronal cells derived from P19 cells but not in undifferentiated P19 or in F9 cells, which do not differentiate into neurons. These results showed that
ATBF1-A
and ATBF1-B transcripts are generated by alternative promoter usage combined with alternative splicing and that the
ATBF1-A
-specific promoter is activated during neuronal differentiation.
...
PMID:Cloning and characterization of an ATBF1 isoform that expresses in a neuronal differentiation-dependent manner. 759 26
