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At least 685 records · Page 38Linked to original sources
PubMed1993

Inhibition of Rev activity and human immunodeficiency virus type 1 replication by antisense oligodeoxynucleotide phosphorothioate analogs directed against the Rev-responsive element.

The interaction between the Rev protein of human immunodeficiency virus type 1 and its highly structured and conserved RNA target, the Rev-responsive element, is required for virus replication. We demonstrate that antisense oligodeoxynucleotide phosphorothioate analogs directed against the Rev-responsive element effectively inhibit Rev activity, as well as human immunodeficiency virus type 1 replication, and are candidates for antiviral therapy.

Base Sequence↗
PubMed1997

Protein and DNA contact surfaces that mediate the selective action of the Phox1 homeodomain at the c-fos serum response element.

The human homeodomain protein Phox1 can impart serum-responsive transcriptional activity to the c-fos serum response element (SRE) by interacting with serum response factor (SRF). This activity is shared with other Paired class homeodomains but not with more distantly related homeodomains. To understand the mechanism of action of Phox1 at the SRE and the basis for the selective activity of Paired class homeodomains in this context, we performed a detailed mutagenesis of the Phox1 homeodomain. We found that amino acid residues that contact the major groove of the DNA are required for SRE activation in vivo, suggesting an in vivo requirement for major-groove DNA contact by the homeodomain. In contrast, substitution of a lysine residue in the N-terminal arm of the Phox1 homeodomain appeared to abolish DNA binding without affecting activity in vivo. Certain substitutions on the exposed surfaces of helices 1 and 2, not required for DNA binding, abolished activity in vivo, suggesting that these surfaces contact an accessory protein(s) required for this activity. We also found that transfer of a single amino acid residue from the surface of Phox1 helix 1 to the corresponding position in the distantly related Deformed (Dfd) homeodomain imparts to Dfd the ability to activate the SRE in vivo. We propose that Phox1 interacts with one or more factors at the SRE, in addition to SRF, and that the specificity of this interaction is determined by residues on the surfaces of helices 1 and 2.

Alanine↗
PubMed1990

Injection of the cAMP-responsive element into the nucleus of Aplysia sensory neurons blocks long-term facilitation.

In both vertebrates and invertebrates, long-term memory differs from short-term in requiring protein synthesis during training. Studies of the gill and siphon withdrawal reflex in Aplysia indicate that similar requirements can be demonstrated at the level of sensory and motor neurons which may participate in memory storage. A single application of serotonin, a transmitter that mediates sensitization, to individual sensory and motor cells in dissociated cell cultures leads to enhanced transmitter release from the sensory neurons that is independent of new macromolecular synthesis. Five applications of serotonin cause a long-term enhancement, lasting one or more days, which requires translation and transcription. Prolonged application or intracellular injection into the sensory neuron of cyclic AMP, a second messenger for the action of serotonin, also produce long-term increases in synaptic strength, suggesting that some of the gene products important for long-term facilitation are cAMP-inducible. In eukaryotic cells, most cAMP-inducible genes so far studied are activated by the cAMP-dependent protein kinase (A kinase), which phosphorylates transcription factors that bind the cAMP-responsive element TGACGTCA. The cAMP-responsive element (CRE) binds a protein dimer of relative molecular mass 43,000, the CRE-binding protein (CREBP), which has been purified and shown to increase transcription when phosphorylated by the A kinase. Here we show that extracts of the Aplysia central nervous system and extracts of sensory neurons contain a set of proteins, including one with properties similar to mammalian CREBPs, that specifically bind the mammalian CRE sequence. Microinjection of the CRE sequence into the nucleus of a sensory neuron selectively blocks the serotonin-induced long-term increase in synaptic strength, without affecting short-term facilitation. Taken together, these observations suggest that one or more CREB-like transcriptional activators are required for long-term facilitation.

Animals↗
PubMed1999

Identification and functional analysis of novel cAMP response element binding protein splice variants lacking the basic/leucine zipper domain.

Two novel cAMP response element binding protein (CREB) splice variants were found by reverse transcription-polymerase chain reaction cloning by using mouse brain RNA as a template. One splice variant, named Delta-14, lacks 14 nucleotides at the beginning of exon 9 of the CREBDelta isoform. The other, named Delta-35, lacks 35 nucleotides at the beginning of exon 8 of CREBDelta. These nucleotide deletions cause frame shifts for codon usage, producing proteins which conserve the major phosphorylation site (Ser(133)) but lack the basic/leucine zipper domain, which is essential for binding to DNA and to other transcription factors. Both variants are widely expressed in peripheral tissues, but are enriched in brain, thymus, and testis. CREBDelta-14 and Delta-35 variant proteins were expressed by using an in vitro translation system and by transfecting into human embryonic kidney 293 cells. Both variants were detected by a CREB antibody that recognizes the CREBDelta amino terminus, but not by an antibody which recognizes the CREBDelta carboxy terminus, as would be predicted based on the frame shift. Activation of the cAMP pathway increased phospho-CREB immunoreactivity, indicating that these variants are substrates of cAMP-dependent protein kinase. In addition, immunocytochemical analysis demonstrated that CREBDelta-14 and Delta-35 are primarily cytosolic, whereas CREBalpha is predominantly in the nucleus. Finally, expression of CREBDelta-14 or Delta-35 decreased cAMP responsive element-chloramphenicol acetyltransferase reporter activity, demonstrating that both can function as repressors of endogenous CREB.

Alternative Splicing↗
PubMed1998

Analysis of DNA binding proteins associated with hemin-induced transcriptional inhibition. The hemin response element binding protein is a heterogeneous complex that includes the Ku protein.

Hemin inhibits transcription of the tartrate resistant acid phosphatase (TRAP) gene. Using deletion mutagenesis of the mouse TRAP 5'-flanking region, we previously identified a 27-bp DNA segment containing a central GAGGC tandem repeat sequence (the hemin response element [HRE]), which bound nuclear proteins (hemin response element binding proteins [HREBPs]) from hemin-treated cells and appeared to be responsible for mediating transcriptional inhibition in response to hemin. We now have used affinity binding to HRE-derivatized beads to identify four HREBP components with apparent molecular masses of 133-, 90-, 80-, and 37-kD, respectively. The 80- and 90-kD components correspond to the p70 and p80/86 subunits of Ku antigen (KuAg) as documented by partial amino acid microsequencing of tryptic digests and immunologic reactivity. Based on reactivity of the HREBP gel shift band with antibodies to the redox factor protein (ref1) in shift Western experiments, it is shown that the 37-kD component represents ref1. The 133-kD component appeared to be a unique protein. KuAg participation in HREBP complexes was specific as it was present in HREBPs bound to HRE microcircles. Results of depletion/reconstitution experiments suggested that KuAg does not bind alone or directly to HRE DNA, but does so only in conjunction with the 133- and/or 37-kD proteins. We conclude that HREBP is a heterogeneous complex composed of KuAg, ref1, and a unique 133-kD protein. We speculate that the role of heme may be to promote interactions among these components, thereby facilitating HRE binding and downregulation of hemin responsive genes.

Acid Phosphatase↗
PubMed1996

An IL-2 response element in the human IL-2 receptor alpha chain promoter is a composite element that binds Stat5, Elf-1, HMG-I(Y) and a GATA family protein.

Expression of the human interleukin-2 (IL-2) receptor alpha chain gene is potently upregulated by its own ligand, IL-2. In this study, we characterize an essential upstream IL-2 response element that contains both consensus and non-consensus GAS motifs, two putative Ets binding sites (EBS), one of which overlaps the consensus GAS motif, and a GATA motif, which overlaps the non-consensus GAS motif. We demonstrate that although the individual components of this element do not respond to IL-2, together they form a composite element capable of conferring IL-2 responsiveness to a heterologous promoter. Multiple factors including Stat5, Elf-1, HMG-I(Y) and GATA family proteins bind to the IL-2 response element and mutation of any one of these binding sites diminishes the activity of this element. An unidentified Ets family protein binds to the EBS overlapping the consensus GAS motif and appears to negatively regulate the human IL-2R alpha promoter. Thus, IL-2-induced IL-2R alpha promoter activity requires a complex upstream element, which appears to contain binding sites for both positive and negative regulatory factors.

Base Sequence↗
PubMed2002

A conserved intronic response element mediates direct p53-dependent transcriptional activation of both the human and murine bax genes.

Both the human and the mouse bax promoters contain p53 binding sites which are sufficient to confer p53-dependent transcriptional activation in a heterologous setting. Nevertheless in the context of the bax promoter, these sites do not mediate a p53-dependent response, suggesting that bax may not be a direct transcriptional target of p53. Here, data are presented identifying a conserved p53 response element in the first intron of both the human and the murine bax genes. This element both in isolation and in the context of the first intron conferred p53-dependent transcriptional activation upon a minimal promoter. Electrophoretic mobility shift assays demonstrated that this sequence also is capable of mediating sequence specific binding to p53. p53 effectively activated transcription through both human and murine bax gene reporter constructs, whereas deletion of the intronic response element abrogated the p53-responsiveness of both reporters. Interestingly, tumor-derived mutants of p53 which are defective in inducing an apoptotic response retain the ability to activate transcription via the bax intronic p53 site. Since these mutants are transcriptionally inactive on the p53 site in the bax promoter, the ability of these mutants to up-regulating endogenous bax mRNA levels supports a role for the intronic element in p53-dependent up-regulation of bax expression. Taken together, these results show the requirement for a novel intronic element in the p53-dependent transcriptional activation of bax, and demonstrate that bax is indeed a direct and evolutionarily conserved transcriptional target of p53.

Animals↗
PubMed2003

Two functionally divergent p53-responsive elements in the rat bradykinin B2 receptor promoter.

Although p53 is known to have dual functions as a transcriptional activator and repressor, there has not been an example where both p53-activating and -repressing elements reside within one target promoter. Previous work from this laboratory defined two different p53 response elements, termed P1 and P2, located at nucleotide positions -70 and -707, respectively, in the rat bradykinin B2 receptor promoter. In this study, through manipulation of the DNA sequence and context, we demonstrate opposing roles for P1 and P2 as transcriptional activator and repressor, respectively. Deletion of P1 abrogates p53-mediated activation. P1 maintains its role as an activator upon relocation to the P2 site and activates transcription from a heterologous promoter construct. Thus, P1 is a bona fide positive p53-response element. In contrast, deletion of P2 enhances P1-induced activation. P2 represses transcription when substituted for P1 or when relocated midway between P1 and P2. P2-mediated repression is sequence-dependent, because it is reversed to activation when P2 is substituted by the P1 or p53 consensus sequences. Moreover, site-directed mutagenesis that converts P2 to a higher affinity p53-binding site results in transcriptional activation rather than repression. Surprisingly, P2 strongly activates a heterologous promoter. Thus, P2-mediated transcriptional repression is both sequence- and context-dependent. Investigations into the mechanisms of P2-mediated repression indicate that it is trichostatin-insensitive and unaffected by CBP or mutation of the minimal repression C-terminal domain of p53. However, gel shift assays suggest that p53 competes with other transcriptional activators for binding to overlapping binding sequences within the P2 element. In conclusion, this study provides a rare example of a transcription factor having two divergent functional effects that are sequence- and context-dependent. The interplay of P1 and P2 may be important in the regulation of bradykinin B2 receptor gene expression in response to inflammatory stress and during development.

Animals↗
PubMed1998

The role of the T-box for the function of the vitamin D receptor on different types of response elements.

The nuclear hormone 1alpha,25-dihydroxyvitamin D3(VD) mainly functions through a heterodimer formed between the VD receptor (VDR) and the retinoid X receptor (RXR). This transcription factor complex specifically recognizes DNA sequences, referred to as VD response elements (VDREs), that are formed by two hexameric core binding motifs arranged either as direct repeats spaced by 3 nt (DR3) or inverted palindromes with nine intervening nucleotides (IP9). Gel shift clipping assays provided the first evidence that VDR-RXR heterodimers form different conformations on these two types of VDREs. Since the T-box within the C-terminal extension of the receptor DNA binding domain (DBD) was previously shown to form a dimerization interface with the partner receptor DBD when bound to DR-type response elements, all six amino acid residues of the VDR T-box were investigated for their role in VDR-RXR heterodimer complex formation on DR3- and IP9-type VDREs. Interestingly, the residue Phe93 (F93) was found to be critical on both types of VDREs, whereas the role of the residue Ile94 (I94) was found to depend on ionic strength of the binding reaction and the nature of the VDRE. However, under physiological conditions I94 was also shown to be critical on both VDRE types. The monitored differences between the two VDR-containing protein-DNA complexes helps in an understanding of the differential action of the nuclear hormone VD and its therapeutically important analogues.

Amino Acid Sequence↗
PubMed1995

Cell type-specific regulation of transcription by cyclic adenosine 3,'5'-monophosphate-responsive elements within the calcitonin promoter.

A cAMP-induced enhancer was previously mapped to nucleotides -255 to -85 of the calcitonin (CT) gene 5'-flanking DNA. To determine the functional cis-acting elements within this region, we transfected medullary thyroid carcinoma (MTC) cells with CT 5'-flanking DNA/GH fusion genes containing potential cAMP-responsive elements and assessed their transcriptional activities with and without cAMP. In CT-expressing MTC cells (the TT line), we identified by deletions and point mutations three transcriptionally active motifs: a cAMP-responsive element (CRE), TGACGTCA, at -253 to -246, and a hybrid site containing a CRE-like element (CREL; TGACCTCA, -169 to -162) adjacent to an equally transcriptionally active octamer (O) sequence (ATG-CAAAT, -161 to -154). These three motifs acted synergistically and their transcriptional activity was completely dependent on cAMP. In HeLa cells their synergistic activity was more constitutive than cAMP induced, whereas in CT-negative MTC cells (the RO-D81-1 line) these motifs were inactive. Gel mobility shift assays with antibodies against CRE-binding protein (CREB) and activating transcription factor 1 (ATF-1) showed that both CREB and ATF-1 interacted with the CRE in MTC cells, whereas in HeLa cells only ATF-1 bound to the CRE. Specific binding to the CREL/O motif was detectable in extracts from tumors induced by injection of TT cells but not in extracts from any of the three cultured cell lines. We conclude that cAMP-induced transcription of the CT gene is modulated in a cell-specific manner by the CRE and the CREL/O elements.

Base Sequence↗
PubMed1990

Association of glucocorticoid receptors with prostate nuclear sites for androgen receptors and with androgen response elements.

Ventral prostate glands of intact normal rats contained low levels (2500 molecules/cell) of high-affinity (dissociation constant (Kd) 0.57 nmol/l) glucocorticoid receptors (GR). Levels of GR increased 2.8-fold 1 day after castration, and 4.3-fold 3 days after castration. Nuclear GR increased from a normal value of 1150 molecules/nucleus to 5200 molecules/nucleus 3 days after castration. The greater increase in intranuclear GR was in that associated with oligomeric chromatin. Although nuclear GR never approached the normal population of nuclear androgen receptors (AR; approximately 16000 molecules/nucleus), the selective rise in chromatin-associated receptors ensured that almost 60% of chromatin sites remained occupied. GR associated with prostate nuclear structures in a similar manner to AR, and exogenous GR bound saturably and with high affinity (Kd 100 pmol/l) to a similar number of sites as did AR. Both steroid receptors apparently competed for the same sites. In DNA-cellulose competition analyses, synthetic oligonucleotides containing glucocorticoid response elements or putative androgen response elements competed similarly against immobilized non-specific DNA for both AR and GR. In view of these data and information from other sources, it is probable that the role of GR in the prostate should be assessed with a view to understanding its action under conditions of androgen deprivation.

Animals↗
PubMed2002

Ku86 autoantigen related protein-1 transcription initiates from a CpG island and is induced by p53 through a nearby p53 response element.

The human Ku86 gene and an isoform, KARP-1 (Ku86 autoantigen related protein-1), encode overlapping, but differentially regulated, transcripts. Ku86 is constitutively transcribed at high levels and, although it plays a seminal role in DNA double-strand break repair, its expression is not induced by DNA damage. KARP-1, in contrast, is expressed constitutively only at low levels and its expression is induced by DNA damage in a p53-dependent fashion. The regulatory elements promoting KARP-1 gene expression and p53 responsiveness, however, were unknown. Here, we report that a strong DNase I hypersensitive site (DHS) resides approximately 25 kb upstream from the Ku86 promoter. This DHS is encompassed by a hypomethylated CpG island. Reporter assays demonstrated that this region corresponded to a promoter(s), which promoted transcription of peroxisomal trans-2-enoyl CoA reductase in the centromeric direction and KARP-1 in the telomeric direction. KARP-1 primer extension products were mapped to this CpG island in the correct transcriptional orientation confirming that KARP-1 transcription initiates from this site. Moreover, a p53 response element within the first intron of the KARP-1 transcriptional unit was identified using chromatin immunoprecipitation and antibodies specific to activated forms of p53. These data expand our understanding of this important DNA repair locus.

5' Flanking Region↗
PubMed1999

Experience-dependent increase in cAMP-responsive element binding protein in synaptic and nonsynaptic mitochondria of the rat hippocampus.

Cyclic AMP-responsive element binding protein (CREB) plays a pivotal role in the formation of long-term memory in Drosophila, Aplysia, mice and rats. Recently, we were able to demonstrate that CREB and its serine 133 phosphorylated form p-CREB are localized in synaptic and nonsynaptic mitochondria of the rat brain. Here we report on the effect of a one-trial inhibitory avoidance training procedure on mitochondrial CREB from the rat hippocampus. This aversively motivated training task is associated with a time-dependent increase (34-35%) in both p-CREB and CREB immunoreactivities detected in synaptic mitochondria of the hippocampus. In nonsynaptic mitochondria, p-CREB levels increased in both trained and shocked animals. In addition to CREB, two CRE-element binding repressors, CREB-2 and CREM-1, were also detected in purified brain mitochondria. No changes were observed in CREB-2 and CREM-1 immunoreactivities in hippocampal synaptic mitochondria after an inhibitory avoidance training. Taken together the present findings represent the first evidence showing that brain mitochondrial CREB may participate in plasticity-dependent changes associated with a behavioural training procedure.

Animals↗
PubMed1996

cAMP-response element modulator tau is a positive regulator of testis angiotensin converting enzyme transcription.

Testis angiotensin-converting enzyme (ACE) is a unique form of ACE, only produced by male germ cells, and results from a testis-specific promoter found within the ACE gene. We have investigated the role of cAMP-response element modulator (CREM)tau in testis ACE transcription. In gel shift experiments, testes nuclear proteins retard an oligonucleotide containing the cAMP-response element (CRE) found at position -55 in the testis ACE promoter. Anti-CREM antibody supershifts this complex. Competitive gel shift shows that recombinant CREM tau protein and testis nuclear proteins have a similar specificity of binding to the tests ACE CRE. Functional analysis using in vitro transcription and transfection studies also demonstrate that CREM tau protein is a transcriptional activator of the testis ACE promoter. Western blot analysis identifies CREM tau protein in the protein-DNA complex formed between nuclear proteins and the testis ACE CRE motif. This analysis also identified other CREM isoforms in the gel-shifted complex, which are thought to be CREM tau 1/2, CREM alpha/beta, and S-CREM. These data indicate that CREM tau isoforms play an important role as a positive regulator in the tissue-specific expression of testis ACE.

Animals↗
PubMed1999

Identification of a cAMP response element within the glucose- 6-phosphatase hydrolytic subunit gene promoter which is involved in the transcriptional regulation by cAMP and glucocorticoids in H4IIE hepatoma cells.

The expression of a luciferase reporter gene under the control of the human glucose 6-phosphatase gene promoter was stimulated by both dexamethasone and dibutyryl cAMP in H4IIE hepatoma cells. A cis-active element located between nucleotides -161 and -152 in the glucose 6-phosphatase gene promoter was identified and found to be necessary for both basal reporter-gene expression and induction of expression by both dibutyryl cAMP and dexamethasone. Nucleotides -161 to -152 were functionally replaced by the consensus sequence for a cAMP response element. An antibody against the cAMP response element-binding protein caused a supershift in gel-electrophoretic-mobility-shift assays using an oligonucleotide probe representing the glucose 6-phosphatase gene promoter from nucleotides -161 to -152. These results strongly indicate that in H4IIE cells the glucose 6-phosphatase gene-promoter sequence from -161 to -152 is a cAMP response element which is important for the regulation of transcription of the glucose 6-phosphatase gene by both cAMP and glucocorticoids.

Base Sequence↗
PubMed2005

Kaposi's sarcoma-associated herpesvirus/human herpesvirus 8 replication and transcription activator regulates viral and cellular genes via interferon-stimulated response elements.

Kaposi's sarcoma-associated herpesvirus (also called human herpesvirus 8 [HHV-8]) replication and transcription activator (RTA) is apparently necessary and sufficient for the switch from viral latency to lytic replication. RTA may regulate open reading frame (ORF) K14 (viral OX-2 homologue) and ORF74 (viral G-protein-coupled receptor homologue) genes through an interferon-stimulated response element (ISRE)-like sequence (K14 ISRE) in the promoter region. RTA strongly activated a K14 ISRE-containing K14-ORF74 promoter reporter construct and a heterologous promoter reporter construct containing K14 ISRE. RTA could bind to K14 ISRE and other ISREs, activate promoter reporter constructs from interferon-simulated genes (ISGs), and selectively induce three endogenous ISGs in primary endothelial cells: ISG-54, myxovirus resistance protein 1 (MxA), and stimulated trans-acting factor of 50 kDa. In addition, a region in the RTA DNA-binding domain has been identified with certain sequence similarity to the DNA-binding domains of the interferon regulatory factor (IRF) family. Mutation in one conserved amino acid within this region reduced the ability of RTA to bind to ISRE as well as other RTA response elements. Furthermore, the mutant failed to activate RTA-responsive promoters and to induce viral lytic gene expression. The mutation at the same conserved amino acid residue in IRF-7 drastically reduced its ability to bind to DNA and to activate the beta interferon promoter. The sequence and functional similarities between RTA and IRFs suggest that the HHV-8 RTA may usurp the cellular IRF pathway.

Amino Acid Sequence↗
PubMed1996

Vitamin D receptor interactions with the murine osteopontin response element.

The nature of the DNA binding interactions of the human vitamin D receptor (hVDR) with the murine osteopontin vitamin D response element (mOP VDRE) was examined. Both recombinant hVDR and human retinoid X receptor beta (hRXRbeta) proteins were obtained from baculovirus-infected Sf9 insect cells. Mixing extracts of the two recombinant proteins resulted in the strong, specific formation of a slower migrating complex in the electrophoretic mobility shift assay. Crude extracts of the expressed hVDR alone were also capable of binding with high affinity to the mOP sequence, and this binding was enhanced in the presence of 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3). Competition experiments confirmed the specificity of this interaction and revealed that the human osteocalcin VDRE was a poor competitor for this binding. Ethylation interference footprint analyses of hVDR/hRXRbeta and hVDR complexes revealed only subtle differences in how these two different VDR-containing complexes interacted with the mOP VDRE. The footprints displayed contact points in both halves of the direct repeat format, confirming the dimeric and major groove interactions of both types of complexes. DNA affinity chromatography of labelled hVDR extracts revealed a peak eluting at ca. 290 mM KC1 that was capable of rebinding to the mOP sequence in gel shift experiments. Ultraviolet (UV) light-crosslinking experiments of hVDR extracts alone to radiolabelled DNA were consistent with the existence of a homodimeric hVDR interaction. Additionally, these experiments confirmed the direct interaction of a hVDR/hRXRbeta heterodimer when mixed extracts were utilized. From these results we infer that homodimers of the hVDR which respond with enhanced DNA binding to particular vitamin D response elements when exposed to 1,25-(OH)2D3 are possible. This may be of functional significance when RXR proteins are limiting or RXR ligand is present within a cell.

Animals↗
PubMed1987

Interaction of two nonhistone proteins with the estradiol response element of the avian vitellogenin gene modulates the binding of estradiol-receptor complex.

The DNA sequence corresponding to the estradiol response element has been synthesized and tested in vitro for the binding of specific proteins. Gel retardation experiments combined with dimethyl sulfate protection experiments revealed that this region binds two nonhistone proteins (NHPs). One of them, NHP-1, has a molecular weight of 70,000 and binds specifically to the dyad symmetry sequence GGTCAGCGTGACC. The NHP-1 can be separated from the estradiol receptor chromatographically; it does not bind estradiol and does not cross-react with an antibody directed against the estradiol receptor. A series of synthetic "mutant" oligonucleotides were tested in a protein-DNA binding competition assay. Deletion of the GCG in the center of the dyad symmetry sequence suppressed the binding of NHP-1 by 90%, and the conversion of any GC pair to an AT pair decreased the affinity of the binding site for NHP-1. Methylation of the two CpGs on both strands of the dyad symmetry sequence decreased the affinity of the binding site for NHP-1 by 60%, whereas hemimethylation of the same structure did not inhibit the binding of NHP-1. NHP-1 and NHP-2, the NHP binding to the DNA next to the dyad symmetry sequence, bind exclusively to double-stranded DNA. NHP-2 has a molecular weight of 60,000. NHP-1 and NHP-2 are neither tissue nor species specific. In vitro reconstitution experiments show that NHP-1 and NHP-2 increase the binding efficiency of the estradiol-receptor complex to the estradiol response element.

Animals↗