Using biomaRt package in R, I have extracted the Transcription Start/Stop Sites of protein coding genes in human genome. So, I have a huge list of TSS. The next step is to get sequences of 1000 bp region upstream and downstream of retrieved TSS coordinates. I figured out that there isn't a function in biomaRt to download sequence upstream and downstream of the TSS. I do appreciate if you could make a suggestion to me.