Disease relevance of RPB4

• The central 100 amino acids of the RPB4 protein were found to be similar to a segment of the major sigma subunit in Escherichia coli RNA polymerase [1].

High impact information on RPB4

• We propose that Rpb4p has a dual function in mRNA decay [2].
• We have determined the crystal structure of the complex between the Methanococcus jannaschii subunits E and F, the archaeal homologs of RPB7 and RPB4 [3].
• Rpb4 and Rpb9 mediate subpathways of transcription-coupled DNA repair in Saccharomyces cerevisiae [4].
• RNA polymerase (Pol) II consists of a 10-polypeptide catalytic core and the two-subunit Rpb4/7 complex that is required for transcription initiation [5].
• Sequence analysis and molecular modeling indicated that the C17/C25 heterodimer likely adopts a structure similar to that of the archaeal RpoE/RpoF counterpart of the Rpb4/Rpb7 complex [6].

Biological context of RPB4

• We have also shown here that transcriptional activation by artificial recruitment of the TATA-binding protein (TBP) to the promoter is also defective in the absence of RPB4 [7].
• The same motif is also seen in the structure of the F subunit, suggesting a structural link between A14 and the RPB4/C17/subunit F family, even in the absence of direct sequence homology [8].
• To examine this hypothesis, we used two-dimensional gel electrophoresis to analyze the protein expression pattern of the rpb4 null mutant in response to heat shock, oxidative stress, osmotic stress, and in the post-diauxic phase [9].
• The RPB4 subunit, although not essential for mRNA synthesis or enzyme assembly, was essential for normal levels of RNA polymerase II activity and indispensable for cell viability over a wide temperature range [1].
• The RPB4 gene was cloned and sequenced, and its identity was confirmed by amino acid sequence analysis of tryptic peptides from the purified subunit [1].

Anatomical context of RPB4

• We show that transcriptional activation in response to either a cell wall stress or to growth in the presence of elevated salt concentrations is minimally affected by the loss of RPB4 function [10].

Associations of RPB4 with chemical compounds

• We also constructed an S. pombe thiamine-dependent rpb4 shut-off system [11].
• Furthermore, by chemical cross-linking, glutathione S-transferase pulldown, and affinity chromatography, the Fcp1-interacting subunit of pol II was identified as Rpb4, which plays regulatory roles in transcription [11].
• We found that genes involved in galactose metabolism were dependent on the presence of Rpb4 irrespective of the environmental condition [12].
• Wild type enzyme devoid of B32 and B16.5 subunits can be obtained after a mild urea treatment [13].
• Sucrose gradient and immunoprecipitation experiments demonstrated that Rpb4 is present in the cell in excess over the Pol II complex during all growth phases [14].

Other interactions of RPB4

• Whereas RPB7 is essential, RPB4 is dispensable for cellular viability [9].
• However, whereas the levels of several mRNAs are similarly reduced (by about 30%) in rpb4 mutants grown in rich medium at moderate temperature, some transcripts, in particular ZDS1, are more abundant [10].
• The Saccharomyces cerevisiae RPB4 gene is tightly linked to the TIF2 gene [15].
• RPB4 encodes the fourth-largest RNA polymerase II subunit in Saccharomyces cerevisiae [1].
• This result indicates the importance of Fcp1-Rpb4 interaction for formation of the Fcp1/TFIIF/pol II complex in vivo [11].

Analytical, diagnostic and therapeutic context of RPB4

• In SDS-PAGE, AtRPB15.9 migrated as the seventh or eighth largest subunit (i.e. apparent molecular mass of 14-15 kDa) in Arabidopsis RNA polymerase II, whereas RPB4 migrates as the fourth largest subunit (i.e. apparent molecular mass of 32 kDa) in yeast RNA polymerase II [16].

References