| Definition |
The basic component of a promoter trap cassette is a promoterless gene. This gene is not flanked by splice acceptor or donor sites, and thus the gene within a promoter trap can only be expressed if the cassette integrates into the genome within an exon, resulting in a transcriptional fusion. If the promoter trap gene encodes an open reading frame (ORF) and the insertion is in the correct frame, the trap ORF may be translated from this transcriptional fusion either as a translational fusion with ORF sequence of the disrupted endogenous locus, or if an internal ribosome entry site (IRES) or viral 2A-like peptide sequence (which promotes ribosome skipping) is present upstream of the promoter trap ORF, it may be produced as a separate protein expressed under the control of the regulatory sequences of the endogenous locus. Depending on the nature of the gene encoded by the promoter trap cassette, the insertion may directly report the expression pattern of the 'trapped' locus (e.g. if the gene encoded by the cassette is a reporter enzyme or fluorescent protein), or it may be used to drive expression of any gene of interest (e.g. if the gene encoded by the cassette is a driver that form part of a binary expression system). A promoter trap cassette may be inserted into a genome as part of a transgenic construct via transposable-element-mediated transgenesis, or may be inserted directly into a modified endogenous locus via a genome engineering method such as homologous recombination or CRISPR. Promoter trap insertions are usually mutagenic, disrupting the locus into which they have inserted, since termination sequences are usually present at the 3' end of the cassette, truncating the endogenous transcript.[ PubMed:10899970 ] |
Full annotation statements including this term (annotations to child terms are NOT included), and relevant FlyBase records
Relationships