Ultrabithorax and Antennapedia 5' untranslated regions promote developmentally regulated internal translation initiation.
The 5' untranslated regions (UTRs) of the Drosophila Ubx and Antp genes were tested for their ability to promote cap-independent translation initiation. The Ubx and the Antp 5' UTR were inserted between the CAT and lacZ coding sequences in a dicistronic gene and tested for IRES activity in transgenic Drosophila. Northern analysis of the mRNAs showed the presence of the predicted full-length dicistronic mRNAs. High CAT activity was expressed from the first cistron from all of the dicistronic constructs introduced into the fly genome. The dicistronic transgenic strains bearing the Ubx and Antp IRES elements expressed significant levels of beta-galactosidase (betaGAL) from the second cistron whereas little or no betaGAL was expressed in the controls lacking the IRESs. In situ analysis of betaGAL expression in the transgenic strains indicates that expression of the second cistron is spatially and temporally regulated. Although the developmental patterns of expression directed by the Antp and Ubx IRESs overlap, they exhibit several differences indicating that these IRESs are not functionally equivalent.
Ye
X
X
Department of Molecular Biology, Vanderbilt University, Nashville, Tennessee 37235, USA.
Fong
P
P
Iizuka
N
N
Choate
D
D
Cavener
D R
DR
D000818:Animals; D030801:Animals, Genetically Modified; D051943:Antennapedia Homeodomain Protein; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000196:embryology / Q000235:genetics; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D018398:Homeodomain Proteins / Q000235:genetics*; D007763:Lac Operon / Q000235:genetics; D007814:Larva; D009687:Nuclear Proteins; D010442:Peptide Chain Initiation, Translational / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D014157:Transcription Factors; D014162:Transfection
D051943:Antennapedia Homeodomain Protein; C497974:Antp protein, Drosophila; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; C066177:Ubx protein, Drosophila; D015500:Chloramphenicol O-Acetyltransferase