InterPro domain: IPR035622

ZOP1 is a novel plant-specific nucleic acid-binding protein required for both RNA-directed DNA methylation (RdDM) and pre-mRNA splicing. It promotes RNA polymerase IV (Pol IV)-dependent siRNA accumulation, DNA methylation, and transcriptional silencing. As a pre-mRNA splicing factor, ZOP1 associates with several typical splicing proteins as well as with RNA polymerase II (RNAP II and Pol II). It also shows both RdDM-dependent and -independent roles in transcriptional silencing. ZOP1 contains an N-terminal C2H2-type Znf domain and an OCtamer REpeat (OCRE) domain that is usually related to RNA processing [ 1 ].

The OCRE (OCtamer REpeat) domain contains five repeats of an 8-residue motif, which were shown to form beta-strands. Based on the architectures of proteins containing OCRE domains, a role in RNA metabolism and/or signalling has been proposed [ 2 ].

1. The splicing machinery promotes RNA-directed DNA methylation and transcriptional silencing in Arabidopsis. EMBO J. 32, 1128-40
2. OCRE: a novel domain made of imperfect, aromatic-rich octamer repeats. Bioinformatics 21, 699-702