hRPB3 (p33) is a highly conserved subunit shared by all three RNA polymerases. It has been shown to be in close contact to promoter DNA when pol II is recruited into the preinitiation complex. RPB3 has also been implicated in direct protein-protein contacts with transcription factor IIB, Rap30 subunit of transcription factor IIF, and gene-specific modulator proteins, such as the hepatitis B virus transactivator protein X or an inhibitor of pol II, RMP (RPB3-mediating protein). Therefore, RPB3 is facilitating the communication between the pol II core and a variety of basal and gene-specific transcription factors. In the pol II complex, RPB3 interacts with RPB5 and the RPB3–RPB5 interaction is intensified in the presence of three subunits, RPB7, RPB8 and RPB11. RPB3 also makes direct contacts with both RPB1 and RPB2, the two large subunits of the polymerase complex.

Clear and colorless frozen liquid solution

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