Hello,

I reviewed this link 3utr/5utr extraction from Gencode, I want to change and adapt the code as part of an R pipeline, where the genes$type field is replaced. I tried to adapt the code, so it encompassed all UTRs not just protein coding.

working_directory_path <- getwd()

library(GenomicRanges) # From Bioconductor.
library(rtracklayer)

Reference_genome_gtf_path <- file.path(working_directory_path, "gencode.v43.annotation.gtf")

# Load the GTF file containing genomic annotations
GTF <- import(Reference_genome_gtf_path)

# Convert the GTF object to a data frame
genes <- as.data.frame((GTF))


whichCodingTranscripts <- genes$type == "transcript"
allFeaturesTranscripts <- genes$transcript_id

strands <- genes$strand
proteinTranscriptsNames <- allFeaturesTranscripts[whichCodingTranscripts]
whichCDS <- genes$type == "CDS" 
transcriptsCDS <- genes[whichCDS, ]
transcriptsCDS <- split(GRanges(transcriptsCDS$seqnames, IRanges(transcriptsCDS$start, transcriptsCDS$end), transcriptsCDS$strand),
                        factor(allFeaturesTranscripts[whichCDS], levels = proteinTranscriptsNames))
firstCDS <- mapply(function(CDS, strand) {if(strand == '+') {CDS[1]} else {CDS[length(CDS)]}}, transcriptsCDS, strands)
lastCDS <- mapply(function(CDS, strand) { if (strand == '+') CDS[length(CDS)] else CDS[1] }, transcriptsCDS, strands)
whichUTR <- genes$type == "UTR" & allFeaturesTranscripts %in% proteinTranscriptsNames
transcriptsUTR <- genes[whichUTR, ]
transcriptsUTR <- split(GRanges(transcriptsUTR$seqnames, IRanges(transcriptsUTR$start, transcriptsUTR$end), transcriptsUTR$strand),
                        factor(allFeaturesTranscripts[whichUTR], levels = proteinTranscriptsNames))

transcriptsUTR5 <- mapply(function(UTR, CDS, strand) {        
  if (strand == '+') UTR[UTR < CDS[1]] else UTR[UTR > CDS[length(CDS)]]
}, transcriptsUTR, firstCDS, as.list(strands), SIMPLIFY = FALSE)

transcriptsUTR3 <- mapply(function(UTR, CDS, strand) {        
  if (strand == '+') UTR[UTR > CDS[length(CDS)]] else UTR[UTR < CDS[1]]
}, transcriptsUTR, lastCDS, as.list(strands), SIMPLIFY = FALSE)

In the end I want the results of transcriptsUTR5 and transcriptsUTR3 to replace the generic genes$type UTR value.

The code doesn't appear to work.