InterPro domain: IPR045125

This entry represents a group of RNA polymerase II transcriptional coactivators, including Sub1 from budding yeasts, Tcp4 from animals and KIWI/KELP from plants.

Tcp4, also known as p15, is a coactivator that functions cooperatively with TAFs and mediates functional interactions between upstream activators and the general transcriptional machinery. It has a bipartite structure composed of an amino-terminal regulatory domain and a carboxy-terminal cryptic DNA-binding domain [ 1 ]. The DNA-binding activity of the carboxy-terminal is disguised by the amino-terminal p15 domain. Activity is controlled by protein kinases that target the regulatory domain.

Sub1 facilitates elongation by influencing enzymes that modify RNAP II (RNA polymerase II) [ 2 ]. It is required for NHEJ repair of DSBs in plasmid DNA, but not in chromosomal DNA [ 3 ].

KELP has been shown to bind to movement protein (MP) of tomato mosaic virus (ToMV) and interferes with virus cell-to-cell movement [ 4 ].

1. A novel mediator of class II gene transcription with homology to viral immediate-early transcriptional regulators. Cell 78, 525-34
2. The transcriptional coactivator PC4/Sub1 has multiple functions in RNA polymerase II transcription. EMBO J 24, 1009-20
3. Differential requirement for SUB1 in chromosomal and plasmid double-strand DNA break repair. PLoS One 8, e58015
4. Over-expression of putative transcriptional coactivator KELP interferes with Tomato mosaic virus cell-to-cell movement. Mol. Plant Pathol. 10, 161-73