The eukaryotic RPB11 and RPB3 subunits of RNA polymerase (RNAP), as well as their archaeal (L and D subunits) and bacterial (alpha subunit) counterparts, are involved in the assembly of RNAP, a large multi-subunit complex responsible for the synthesis of RNA. It is the principal enzyme of the transcription process, and is a final target in many regulatory pathways that control gene expression in all living cells. At least three distinct RNAP complexes are found in eukaryotic nuclei: RNAP I, RNAP II, and RNAP III, for the synthesis of ribosomal RNA precursor, mRNA precursor, and 5S and tRNA, respectively. A single distinct RNAP complex is found in prokaryotes and archaea, which may be responsible for the synthesis of all RNAs. The assembly of the two largest eukaryotic RNAP subunits that provide most of the enzyme's catalytic functions depends on the presence of RPB3/RPB11 heterodimer subunits. This is also true for the archaeal (D/L subunits) and bacterial (alpha subunit) counterparts.
Comment:The eukaryotic RNAP II RPB11 and RPB3 subunits form a heterodimer, which is involved in RNAP assembly. The dimer stabilizes the association of the two largest RNAP subunits, RPB1 and RPB2. In archaea, the equivalent dimer is composed of subunits L and D. In bacteria, the equivalent dimer is a homodimer of alpha subunits.
Comment:RPB11 (subunit L in archaea) interfaces with the RPB11-like subdomain of RPB3 (subunit D in archaea). The bacterial alpha subunit homodimerizes through its RPB11-like subdomain.
Structure:1I50; Saccharomyces cerevisiae RNAP II RPB11 subunit (1I50_K) heterodimerizes with RPB3 subunit (1I50_C); defined using 3.5A contacts. - View structure with Cn3D