RAP30

RAP30, also known as GTF2F1, is a 30-kilodalton subunit of transcription factor II F (TFIIF) in eukaryotes. It forms a heterodimer with the 74-kilodalton subunit RAP74 (GTF2F2) to constitute the TFIIF complex, a general transcription factor involved in RNA polymerase II–mediated transcription initiation. In humans and many other species, RAP30 is encoded by the GTF2F1 gene and is conserved across eukaryotes, including yeast and plants.

Functionally, RAP30 binds to RNA polymerase II and interacts with other components of the pre-initiation complex, such as TFIIB and TBP, to facilitate promoter loading of Pol II. The RAP30–RAP74 heterodimer helps recruit RNA polymerase II to promoters, stabilizes the polymerase at promoter sites, and modulates initiation efficiency and promoter escape. By contributing to proper assembly and positioning of Pol II at promoters, TFIIF helps ensure accurate transcription start site selection and orderly transition from initiation to elongation.

Biologically, RAP30 plays a essential role in transcription initiation across many promoters. Experimental disruption of RAP30 function often results in diminished transcriptional activity, underscoring its importance in gene expression and cellular regulation.

Structure and interactions are characterized by domains in RAP30 that mediate contact with RNA polymerase II and with RAP74, enabling the integrity of the TFIIF heterodimer within the transcription machinery. Structural and biochemical studies of the Pol II–TFIIF complex have revealed contacts between RAP30, Pol II subunits, and other initiation factors.

Clinical relevance for RAP30 is not tied to a single disease, but components of transcriptional machinery, including RAP30, can influence cellular processes and disease risk when dysregulated.