InterPro domain: IPR012890

This entry includes GCFC2 and PAXBP1 from humans, and ILP1 from Arabidopsis thaliana. GCFC2 is involved in pre-mRNA splicing through regulating spliceosome C complex formation [ 1 ]. ILP1 and its orthologue in mouse have been shown to be repressors of cyclin genes. In Arabidopsis, all members of the CYCLINA2 family are repressed, and in mouse cyclin A2. The CYCLINA2 cyclins control endoreduplication, in which DNA is replicated but the cell cyle continues without cell division leading to polyploidy. ILP1 therefore regulates endoreduplication through control of CYCA2 expression in Arabidopsis [ 2 ]. ILP1 has been shown to be required for efficient splicing [ 3 ].

It's worth noting that GCFC2 was originally thought to be a DNA-binding transcriptional repressor. However, later work showed that the original sequence was a chimera and that the DNA-binding activity was derived from the incorrect N-terminal sequence [ 4 ].

1. Identification of a novel component C2ORF3 in the lariat-intron complex: lack of C2ORF3 interferes with pre-mRNA splicing via intron turnover pathway. Genes Cells 19, 78-87
2. Increased level of polyploidy1, a conserved repressor of CYCLINA2 transcription, controls endoreduplication in Arabidopsis. Plant Cell 18, 2452-68
3. NTR1 is required for transcription elongation checkpoints at alternative exons in Arabidopsis. EMBO J. 34, 544-58
4. Molecular analysis of the GCF gene identifies revisions to the cDNA and amino acid sequences(1). Biochim Biophys Acta 1447, 125-31