Dear All. Could someone please check if my understanding of transcription from both sense and antisense strands of DNA are correct. I am also confused about transcription of genes that exist in the opposite directions.
1- Both sense (5-3’) and antisense (3’-5’) strands of DNA can be transcribed (such as Xist and Tsix transcription; see attached file). However as transcription progresses from 5’->3’ direction, I do not know how sense strand can be transcribed as I think the transcription on this strand would be from 3’->5’? 2- Do genes that can produce both sense and antisense transcripts contain promoters on both strands in the opposite directions of each other? If this is true I think transcription on both strands do not occur simultaneously as polymerases will collide. Probably transcription on different strands will occur under different conditions in the presence of different transcription factors. 3- For a gene that is located in the opposite direction in the DNA (such as BRCA1), on which strand of DNA does the transcription occur? If it occurs on the antisense strand does that mean that the DNA denatures so mush so that promoter at the end of the gene is exposed to transcription machinery on the antisense strand?
Thank you very much for your help!