Which approach do you find useful to extract gene features (promoters, 5'UTR, exons, introns, 3'UTR ) from the annotation file (genes.gtf) of a reference genome e.g. the iGenomes UCSC hg38?
I often use the functions available in the GenomicFeatures bioconductor package, e.g. makeTxDbFromGFF, promoters, genes, transcripts, ...
library(GenomicFeatures)
txdb <- makeTxDbFromGFF("genes.gtf", format="gtf")
promoters(txdb) # extracting promoters
exons(txdb) # extracting exons
However I was wondering which other strategies are commonly used in general when genes features are needed. Any ideas would be helpful.
1 answer
Use grep or awk, e.g.:
$ awk '$3=="exon"' genes.gtf > exons.gtf
You can use BEDOPS gtf2bed to convert a GTF file to BED, and then use BEDOPS bedops and bedmap tools to calculate subsets of that BED file.
This approach can be used, for example, to get exon-intron junctions, intergenic regions, annotations that overlap SNPs with disease phenotypes of interest in promoter regions, etc. etc.
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