The transcription of ribosomal RNA genes by RNA polymerase I (Pol I) is tightly coordinated with the growth state of the cell. In addition to Pol I, transcription of ribosomal genes requires the trans-activating factor UBF (upstream binding factor). UBF functions by binding to DNA elements within the RNA gene promoter and enhancer regions and directly associating with Pol I, tethering it to the promoter complex. Two UBF proteins, of 97 kDa and 94 kDa, arise from the same gene as a result of alternative mRNA splicings. UBF activity is regulated by several dependent casein kinase II phosphorylates at the carboxy terminus of UBF on serine residues. The retinoblastoma susceptibility gene product, Rb, when not bound to E2F family members, inhibits UBF activity. Expression of RNA may also be negatively regulated by the 70 kDa and 86 kDa Ku antigens.

推荐稀释比 WB:1/500-1/1000;IHC:1/50-1/200