RNA-binding motif protein 8 (RBM8), also termed binder of OVCA1-1 (BOV-1) or RNA-binding protein Y14, is one of the components of the exon-exon junction complex (EJC) []. It has two isoforms, RBM8A and RBM8B, both of which are identical except that RBM8B is 16 amino acids shorter at its N terminus []. Three-dimensional modelling of the RBM8 RRM domain indicates that the sequences fold into an RNA-binding domain, forming a hydrophobic core between a β-sheet and two helices. The human RBM8A protein is ubiquitously expressed; the protein is localised predominantly in the cell nucleus and diffused throughout the cytoplasm []. It preferentially associates with mRNAs produced by splicing, including both nuclear mRNAs and newly exported cytoplasmic mRNAs. Evidence suggests the protein remains associated with spliced mRNAs as a tag to indicate the position of spliced introns. Human RBM8A protein specifically binds to MAGOH, the human homologue of Drosophila mago nashi, a protein required for normal germ plasm development in the Drosophila embryo []; a similar association occurs with the Drosophila RBM8 protein, Tsunagi []. The RBM8A and RBM8B protein sequences contain a putative bipartite nuclear localisation signal []at the N terminus, as well a stretch of glycine residues. In addition, the RRM contained within RBM8A and RBM8B contains one set of the two consensus nucleic acid-binding motifs, RNP-1 and RNP-2, characteristic of heterogeneous nuclear ribonucleoprotein (hnRNP).
This entry corresponds to the RNA recognition motif of RBM8. RNA-binding protein RBM8, also termed binder of OVCA1-1 (BOV-1) or RNA-binding protein Y14, is one of the components of the exon-exon junction complex (EJC) []. It has two isoforms, RBM8A and RBM8B, both of which are identical except that RBM8B is 16 amino acids shorter at its N terminus []. RBM8, together with other EJC components (such as Magoh, Aly/REF, RNPS1, Srm160, and Upf3), plays critical roles in postsplicing processing, including nuclear export and cytoplasmic localization of the mRNA, and the nonsense-mediated mRNA decay (NMD) surveillance process. RBM8 binds to mRNA 20-24 nucleotides upstream of a spliced exon-exon junction. It is also involved in spliced mRNA nuclear export, and the process of nonsense-mediated decay of mRNAs with premature stop codons. RBM8 forms a specific heterodimer complex with the EJC protein Magoh which then associates with Aly/REF, RNPS1, DEK, and SRm160 on the spliced mRNA, and inhibits ATP turnover by eIF4AIII, thereby trapping the EJC core onto RNA [, ].RBM8 contains an N-terminal putative bipartite nuclear localization signal, one RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), in the central region, and a C-terminal serine-arginine rich region (SR domain) and glycine-arginine rich region (RG domain) [].
