InterPro domain: IPR016194

This superfamily represents the Spen Paralogue and Orthologue C-terminal (SPOC) domain and its structural homologues. This domain has a closed beta-barrel fold of complex topology. Proteins that carry a SPOC-like domain include:

• Spen proteins, such as SHARP (SMRT/HDAC1-associated repressor protein), which carry a SPOC domain at the C-terminal and an RNA-binding motif in the N-terminal; Spen proteins regulate the expression of key transcriptional effectors in diverse signalling pathways, the SHARP protein being a component of transcriptional repression complexes in both nuclear receptor and Notch/RBP-Jkappa signalling pathways [ 1 ].

• The middle domains of Ku70 and Ku80 (which includes the C-terminal alpha-helical arm and the DNA encircling insertion); the Ku heterodimer, which is composed of Ku70 and Ku80 subunits, contributes to genomic integrity through its ability to bind DNA double-strand breaks and facilitate repair by the non-homologous end-joining pathway [ 2 ].

1. A conserved structural motif reveals the essential transcriptional repression function of Spen proteins and their role in developmental signaling. Genes Dev. 17, 1909-20
2. Structure of the Ku heterodimer bound to DNA and its implications for double-strand break repair. Nature 412, 607-14