Genomic coordinates of predicted binding pocket
It turns out there is a tool that does this beautifully.  I used the proteinToGenome function from the ensembldb package.

The code looks like this:

# Define the Ensemble database object for the 
edbX &lt;- filter(EnsDb.Hsapiens.v75, filter = ~ seq_name == "X") 
# Set the first and last amino acid you want to convert and the ensembl protein id
GAGE10_prt &lt;- IRanges(start = 5, end = 9, names = "ENSP00000385415")
# Perform the conversion.  GAGE10_prt is an object that has the coordinates
GAGE10_prt &lt;- proteinToGenome(GAGE10_prt, edbX)