 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 helicases , which unwind the double @-@ stranded DNA molecule to facilitate access to it , RNA polymerases , which synthesize the growing RNA molecule , topoisomerases , which change the amount of supercoiling in DNA , helping it wind and unwind , as well as a large variety of transcription factors that regulate expression . 
 Since the nucleus <a href='drop_aux' title='1'><mark>is</mark></a>the site of transcription , it also <a href='uninflect' title='2'><mark>contains</mark></a> a variety of proteins <a href='null_relcl' title='3'><mark>that</mark></a>either directly mediate transcription or are involved in regulating the process . These proteins include helicases , which unwind the double @-@ stranded DNA molecule to facilitate access to it , RNA polymerases , which synthesize the growing RNA molecule , topoisomerases , which change the amount of supercoiling in DNA , helping it wind and unwind , as well as a large variety of transcription factors <a href='null_relcl' title='4'><mark>that</mark></a>regulate expression . 
Since da nucleus the site of transcription , it also contain a variety of proteins either directly mediate transcription or r involved in regulating the process . dem proteins include helicases , which unwind tdadouble @-@ stranded DNA molecule to facilitate access to it , RNA polymerases , which synthesize the growing RNA molecule , topoisomerases , which change thdamount of supercoiling in DNA , helping it wind and unwind , as well as a bigass variety of transcription factors regulate expression .