[subroutine]

How would non-coding DNA help with protein folding when translation happens outside the nucleus?

It's possible that upstream UTRs impact RNA transcription rates, but I'd be surprised if UTRs mediate protein folding.

[Someone]

Non-coding = "not translated into proteins", not "isn't used". Some non-coding DNA produces non-coding RNA, including transfer RNAs (https://en.wikipedia.org/wiki/Non-coding_RNA), which help in protein construction.

[subroutine]

This makes sense given we know that some nontranslated RNA has biological activity , like tRNA and rRNA. I was under the impression that "junk" DNA referred to DNA that was not transcribed.

[dekhn]

nearly all DNA is transcribed at some low rate (this has been experimentally determined) but it seems probable that most long stretches of non-coding DNA contain little to no functional elements and could be replaced or removed with no observable functional effect.

[arca_vorago]

I wanted to say something about RNA so maybe your onto something, but alas, I may be simply wrong.