Isn't this article just describing one of the functions of DNA promoters, gene expression?
No, because promoters are usually upstream of protein coding regions. This paper claims that transcription factors, which are known for binding promoters and enhancers, also sometimes bind the protein coding regions themselves. This may create additional evolutionary constraints on the protein code, which could affect codon bias.
It's certainly novel, and quite interesting, but not totally revolutionary as the press releases like to insinuate.
is it about which part of the gene is encoding for proteins in means of introns and exons?