A promoter reported in cDNA corresponding to IRES sequence: yes
The total number of notable open-reading frames (ORFs): 1
Summary of possible issues when IRES cDNA is experimentally transcribed in vivo:
Summary of experiments studying integrity of the in vivo transcripts in a particular host:
Integrity (uniformity) of mRNA tested using Northern-blot: not_tested
Integrity (uniformity) of mRNA tested using RNase protection: not_tested
Integrity (uniformity) of mRNA tested using 5'-RACE: not_tested
Integrity (uniformity) of mRNA tested using primer extension : not_tested
Integrity (uniformity) of mRNA tested using RT-PCR: heterogeneous_population_of_molecules_found
Integrity (uniformity) of mRNA tested using real-time quantitative polymerase chain reaction (rtqPCR): not_tested
Integrity (uniformity) of mRNA tested using RNAi: heterogeneous_population_of_molecules_found
Integrity (uniformity) of mRNA tested using S1 nuclease mapping: not_tested
Cryptic promoter presence was confirmed by expression from a promoter-less plasmid: no_promoter_confirmed
Cryptic promoter presence was confirmed in an experimental setup involving inducible promoter: not_tested
Integrity (uniformity) of mRNA molecules or possible promoter presence expressed in vivo was tested using another method, please specify in Remarks: not_tested
Summary of experiments studying integrity of the in vivo transcripts in a particular host:
Integrity (uniformity) of mRNA tested using Northern-blot: not_tested
Integrity (uniformity) of mRNA tested using RNase protection: not_tested
Integrity (uniformity) of mRNA tested using 5'-RACE: not_tested
Integrity (uniformity) of mRNA tested using primer extension : not_tested
Integrity (uniformity) of mRNA tested using RT-PCR: not_tested
Integrity (uniformity) of mRNA tested using real-time quantitative polymerase chain reaction (rtqPCR): not_tested
Integrity (uniformity) of mRNA tested using RNAi: not_tested
Integrity (uniformity) of mRNA tested using S1 nuclease mapping: not_tested
Cryptic promoter presence was confirmed by expression from a promoter-less plasmid: promoter_confirmed
Cryptic promoter presence was confirmed in an experimental setup involving inducible promoter: not_tested
Integrity (uniformity) of mRNA molecules or possible promoter presence expressed in vivo was tested using another method, please specify in Remarks: not_tested
The description of the protein encoded in this ORF: X-linked inhibitor of apoptosis
The translational frameshift (ribosome slippage) involved: 0
The ribosome read-through involved: no
The alternative forms of this protein occur by the alternative initiation of translation: no
The ORF absolute position (the base range includes START and STOP codons or their equivalents): 467-1960
Remarks:
For creation of this IRESite record we have used an EST fragment (which matched the described primers) merged
with Refseq mRNA sequence which had incomplete 5'-UTR. van Eden et al. (2004) actually amplified some
sequence from HeLa cells.
The tested cDNA fragment (bases 5-464 in IRESite) contains in its RNA form a splice-acceptor site as confirmed
by 2 additional bicistronic mRNA molecule types found by RT-PCR (Fig. 2). The splicing site is shown in Fig
3A. Existence of the acceptor site was also claimed to be confirmed by other EST records of XIAP mRNA
molecules. The reported splice junction is "5'-AGaAAGGUG-3'". [van Eden et al. (2004)]
In addition, the sequence between 1-434 is not supported by any dbEST data except record GI:28290426
(BX119811) supporting bases 1-484.
Use of a promoter-less plasmid to test for cryptic promoter presence did not reveal any promoter in the tested
region (but authors did not show the actual results in the article). When direct RNA transfection was
performed IRES activity was only observed in 293T cells (2-fold activity of the control empty vector pRL-FL)
while no significant activity was found in HepG2 and HeLa S3 cells. [van Eden et al. (2004)]
RNAi was used to study whether its application decreases Rluc and Fluc activity in the same scale -- which
would confirm that they originate from a physically same mRNA molecule and in turn would confirm that
1) no promoter exists in the DNA region in corresponding the the expected mRNA molecules and
2) no aberrant splicing occurs.
It was found that activity of both luciferases was NOT decreased equivalently. [van Eden et al.
(2004)]
The IRES activity was also shown in rabbit reticulocyte lysates using bicistronic capped and non-capped mRNAs.
[van Eden et al. (2004)]
Bert et al. (2006) tested XIAP IRES in HeLa cells using promoter-less plasmids with or without the enhancer
left in (Figure 2). They showed there is a cryptic promoter activatable when the enhancer is left in.
The IRES absolute position (the range includes START and STOP codons or their equivalents): 5-464
Conclusion: probably_not_IRES
How IRES boundaries were determined: experimentally_determined
The sequence of IRES region aligned to its secondary structure (if available):
Remarks:
"IRES" activity was found to overlap with the polypyrimidine tract, which unfortunately is also involved
in the splicing issues. Mutation of the polypyrimidine tract decreased dramatically by 30-fold the "IRES"
activity although still aberrantly spliced products were detected.
Similarly, mutations of the splice donor/acceptor sites resulted in lower abundance of the alternative
splice variants or even shifted the splice spliced by few bases. None of these approaches could not be used
to completely eliminate the splicing issue with pRL-XIAP-FL plasmid. [van Eden et al. (2004)]
Direct mRNA transfection confirmed only weak IRES activity in 293T cells (95% of the activity detectable
using DNA-based transfection was gone) whereas in HepG2 and HeLa cells it was not statistically significant.
The Fig. 4C,D shows that XIAP IRES seriously underperforms in contrast to HCV IRES both as a capped of
non-capped exogenous transcript. [van Eden et al. (2004)]
Several proteins have been found to interact with XIAP IRES in vitro (Lewis et al. (2007)): p37 (hnRNP A1),
p44, p45, p52 (La autoantigen), p100, p150.
Bert et al. (2006) concluded that despite the cryptic promoter there is "some" IRES activity in XIAP. Further
they report that in direct RNA transfection XIAP IRES is about 5.9x above the negative control while EMCV-R
IRES was 221x above the control (Figure 4).
The IRES absolute position (the range includes START and STOP codons or their equivalents): 305-466
Conclusion: probably_not_IRES
How IRES boundaries were determined: experimentally_determined
The sequence of IRES region aligned to its secondary structure (if available):
There is no Vienna RNA package installed on the server or some error/warning messages were output. Due to that maybe we cannot prepare 2D structures for display. The error/warning message was:
((..(((.................((((......))))...((((((((((..((((((.........)))))).))))...))))))..)))..)))))..))..............((((((.........(((.........))).......)))))).
ERROR: unbalanced brackets in make_pair_table
STDOUT was:
Remarks:
Baranick et al., 2008 and they postulate that most of the "IRES" activity observed so far was due to the
splice artifacts (Fig. 3D).
ITAF description (long): La autoantigen (p52), 52 kDa RNA binding protein, predominantly localized to nucleus, unwinds the dsRNA in
ATP-dependent manner, forms a dimer
3.2.2. Organisms or in vitro systems where this ITAF was functionally studied:
Organism or in vitro system where ITAF was shown:
Necessity of ITAF for translation in this particular organism or system: stimulatory
Method used to demonstrate ITAF effect: in_vitro
In vitro system used to demonstrate ITAF effect: other
Remarks:
HEK 293T cell extracts were used to demonstrate in vitro binding to XIAP RNA. Data from Figure 1A.
ITAF fullname: polypyrimidine tract-binding protein isoform 1
ITAF description (long): polypyrimidine tract-binding protein isoform 1 binds dsRNA with (CCU)n motif where n is at least 3. By SELEX
approach it was found it binds to 5'-CAGCCUGGUGCCUCUCUUUCGG-3' (Singh et al. (1995) Science 268:1173-1176)
but also UCUU or UCUUC within pyrimidine-rich sequence (Perez et al. (1997) RNA3:1334-1347).
3.4.2. Organisms or in vitro systems where this ITAF was functionally studied:
Organism or in vitro system where ITAF was shown:
Necessity of ITAF for translation in this particular organism or system: required_but_available_internally
Method used to demonstrate ITAF effect: both
In vitro system used to demonstrate ITAF effect: other
The organism where action of this ITAF was studied:
Deletion of the XIAP 5' UTR polypyrimidine tract causes a loss of PTB binding and a complete loss of IRES
activity, but does not disrupt the binding of other ITAFs.
Overexpression of PTB represses XIAP IRES activity.
HEK 293T cell extracts were used to demonstrate in vitro binding to XIAP RNA. Data from Figure 8A/B/C.
The absolute position of the experimentally mapped region (the range includes START and STOP codons or their equivalents): 297-469
The underlying nucleic acid sequence and structure of the mapped region:
Rendering structure of XIAP mRNA 173 nt long with energy of -9.20 kcal/mol as calculated by RNAeval using VARNA Java applet with some IRESite improvements (see VARNA modified by IRESite). Hold left mouse button to move structure parts, hold right mouse button to move whole structure, use mouse wheel to zoom. Right mouse-click opens a menu to export into JPG/SVG and many other options.
Remarks:
2D structure of XIAP from Figure 1. Several mutations altering in certain region the structure did not affect
the IRES activity (Figure 7).
4.1.1. Enzymes used to characterize at least partially the 2D structure.
Enzyme or a combination of enzymes used in a single experiment with respective buffer:
ss_experiment_with_enzyme_id: 23
The temperature (in degrees of Celsia): 22
The enzymatic method used to determine the 2D structure: ribonuclease T1
Enzyme or a combination of enzymes used in a single experiment with respective buffer:
Version: 0
pH 7.00
Li+ [mM] 0
Na+ [mM] 0
K+ [mM] 100.00
Mg2+ [mM] 10.00
Ca2+ [mM] 0
Cl- [mM] 110.00
Tris [mM] 10.00
BSA [mM] 0
HEPES [mM] 0
EGTA [mM] 0
EDTA [mM] 0
cacodylate [mM] 0
Enzyme or a combination of enzymes used in a single experiment with respective buffer:
ss_experiment_with_enzyme_id: 24
The temperature (in degrees of Celsia): 22
The enzymatic method used to determine the 2D structure: ribonuclease A
Enzyme or a combination of enzymes used in a single experiment with respective buffer:
Version: 0
pH 7.00
Li+ [mM] 0
Na+ [mM] 0
K+ [mM] 100.00
Mg2+ [mM] 10.00
Ca2+ [mM] 0
Cl- [mM] 110.00
Tris [mM] 10.00
BSA [mM] 0
HEPES [mM] 0
EGTA [mM] 0
EDTA [mM] 0
cacodylate [mM] 0
Enzyme or a combination of enzymes used in a single experiment with respective buffer:
ss_experiment_with_enzyme_id: 25
The temperature (in degrees of Celsia): 22
The enzymatic method used to determine the 2D structure: ribonuclease V1
Enzyme or a combination of enzymes used in a single experiment with respective buffer:
Version: 0
pH 7.00
Li+ [mM] 0
Na+ [mM] 0
K+ [mM] 100.00
Mg2+ [mM] 10.00
Ca2+ [mM] 0
Cl- [mM] 110.00
Tris [mM] 10.00
BSA [mM] 0
HEPES [mM] 0
EGTA [mM] 0
EDTA [mM] 0
cacodylate [mM] 0
Enzyme or a combination of enzymes used in a single experiment with respective buffer:
ss_experiment_with_enzyme_id: 26
The temperature (in degrees of Celsia): 22
The enzymatic method used to determine the 2D structure: ribonuclease T2
Enzyme or a combination of enzymes used in a single experiment with respective buffer: