IRESite record type: plasmid_with_promoter_and_putative_IRES_translationally_characterized
The shape of the nucleic acid molecule translated: linear
The quality of the mRNA/+RNA sequence: our_best_guess
The mRNA/+RNA description:
Bicistronic mRNA containing renilla and firefly luciferases with BCL2 IRES segment in the intercistronic
region. The mRNA is spliced and does not contain the chimeric intron. The sequence ends at its 3'-end right
after the poly(A) signal from bovine growth hormone (BGH) mRNA and thus the 3'-UTR might be slightly wrong (it
is unknown what region of the BGH signal was transcribed and where the poly(A) tail was added).
The mRNA/+RNA sequence represented in the +DNA notation:
Warning: mRNA sequence when devoid of trailing 'A's is still not a substring of the plasmid sequence. Is it because an intron is spliced out? Stay calm then. :-)
Credibility of mRNA sequence: reverse_engineered_sequence_and_should_match_experiment_except_3UTR
The name of the promoter used to express this mRNA: CMV
The in vivo produced transcripts are heterogeneous (due to any of promoter?/splicing?/cleavage?/breakage?): yes
The in vivo produced heterogeneous transcripts occur due to alternative splicing: yes
A promoter reported in cDNA corresponding to IRES sequence: yes
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: 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: weak_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 abbreviated name of this ORF/gene: FLuc-fusion
The description of the protein encoded in this ORF: Firefly luciferase fused N-terminally with 6 extra aminoacid residues (including the initiator ATG) from BCL2
protein.
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: not tested
The ORF absolute position (the base range includes START and STOP codons or their equivalents): 2279-3949
Remarks:
Negligible promoter activity attributable to BCL2 IRES was shown in Fig. 3A using promoter-less plasmid.
Alternatively spliced transcripts from this plasmid were confirmed in Fig. 3C.
The relative translation efficiency in % of this IRES: 140.000
Name of IRES used as the positive control: HCV_type_1b
Name of the plasmid used as the positive control. pRL-HCV-FL
Name of the plasmid used as the negative control. pRL-FL
IRESite Id of the plasmid used as positive control. 131
IRESite Id of the plasmid used as negative control. 119
The relative translation efficiency in % of the positive control: 100.000
The relative translation efficiency in % of the negative control: 2.000
The size (length) of intercistronic region in the positive control: 485
The size (length) of intercistronic region in the negative control: 28
The effect of 5'-cap analogs on translation: not tested
Rapamycin affects translation: not tested
Type of RNA subject to translation: endogenous_nuclear_RNA_Pol_II_transcript
Remarks:
The results from Fig. 3A do not form the supporting evidence for existence of IRES in BCL2 (the direct mRNA
transfection is the key experiment, see IRESite Id: 114 namely its subsection IRESite Translation Id: 97).
They only demonstrate how the luciferase values obtained are biased by presence of the cryptic promoter in HCV
IRES and by the promoter in BCL2 and by aberrant splicing from pRL-BCL2-FL plasmid (where splice acceptor site
was uncovered in BCL2 IRES and which causes alternatively splices with the chimeric intron contained in the
plasmid). Those alternative transcripts are functionally monocistronic (Fig. 3B, C).