RPB3

PF3D7_0923000 (RPB3) is annotated as a putative subunit of the P. falciparum RNA polymerase II complex, and the available corpus characterizes only the activity of that complex rather than RPB3 itself. The Pol II machinery of which RPB3 is a subunit synthesizes antisense RNA at multiple genomic loci in P. falciparum nuclei, an activity sensitive to the Pol II inhibitor alpha-amanitin (PMID:15703443). Nascent RNA profiling further shows this Pol II complex engaged at promoter regions before the major transcriptional burst of the trophozoite stage, implicating Pol II pausing in stage-specific gene regulation across the intraerythrocytic developmental cycle (PMID:28531310). No mechanistic finding directly and specifically interrogating RPB3 (PF3D7_0923000) as an individual subunit—its assembly role, interaction partners within the complex, or an RPB3-specific phenotype—has been characterized in the available corpus; the evidence speaks only to the complex.

1. 2005 Low

   Whether the Pol II machinery is responsible for antisense RNA production in P. falciparum was unresolved; showing alpha-amanitin sensitivity established that the Pol II complex (of which RPB3 is a putative subunit) generates antisense transcripts at multiple loci.

   Evidence Nuclear run-on with single-stranded DNA probes and alpha-amanitin inhibition in synchronized parasite nuclei

   PMID:15703443

   Open questions at the time

   • Does not directly interrogate RPB3 (PF3D7_0923000); the assay reports the whole Pol II complex
   • No RPB3-specific contribution to antisense transcription established
   • No subunit composition or assembly data
2. 2017 Low

   How Pol II activity is timed across the intraerythrocytic cycle was unknown; nascent RNA profiling showed the complex is poised at promoters before the trophozoite transcriptional burst, establishing Pol II pausing as a dominant regulatory mode.

   Evidence Genome-wide nascent RNA sequencing (GRO-seq / nascent RNA profiling) across the intraerythrocytic developmental cycle

   PMID:28531310

   Open questions at the time

   • Reports Pol II complex behavior, not RPB3-specific function
   • No demonstration that RPB3 modulates pausing or promoter engagement
   • No physical or genetic data linking RPB3 to the observed regulatory pattern

• It remains unknown what RPB3 (PF3D7_0923000) contributes as an individual subunit—its role in Pol II assembly, its specific interaction partners, and whether it carries any RPB3-specific regulatory function distinct from the complex.
• No RPB3-specific loss-of-function or localization data
• No structural or interaction mapping of RPB3 within Pol II
• No evidence distinguishing RPB3 function from bulk Pol II activity