| To find out whether these polymerase associated factors ( PAF 53 , 51 , and 49 ) serve a role in growth dependent control of rDNA transcription , we generated polyclonal antibodies against three subunits of murine Pol 1 , RPA 116 , RPA 40 and PAF 53 , and used different experimental approaches , e . g . immunoblot analysis , immunoprecipitation and immunofluorescence studies , to compare the stoichiometry of individual subunits both in different Pol 1 preparations and in extracts from cells grown under different conditions . ^^^ |