 Since the nucleus is the site of transcription , it also contains a variety of proteins that either directly mediate transcription or are involved in regulating the process . These proteins include <unk> , which <unk> the double @-@ stranded DNA molecule to facilitate access to it , RNA <unk> , which synthesize the growing RNA molecule , <unk> , which change the amount of <unk> in DNA , helping it wind and <unk> , as well as a large variety of transcription factors that regulate expression . 
