May play a role in pre-mRNA splicing as component of the spliceosome (By similarity). Acts as an important regulator of the cell cycle that participates in the maintenance of genome integrity (PubMed:21191184, PubMed:23213458, PubMed:25168238, PubMed:15988037). During cell cycle progression in embryonic fibroblast, prevents replication fork collapse, double-strand break formation and cell cycle checkpoint activation (PubMed:21191184). Controls mitotic cell cycle progression and cell survival in rapidly proliferating intestinal epithelium and embryonic stem cells (PubMed:23213458). During the embryo preimplantation, controls different aspects of M phase (PubMed:15988037). During early oocyte growth, plays a role in oocyte survival by preventing chromosomal breaks formation, activation of TP63 and reduction of transcription (PubMed:25168238). Component of the XAB2 complex, a multimeric protein complex composed of XAB2, PRPF19, AQR, ZNF830, ISY1, and PPIE; this complex binds preferentially to RNA. Interacts with XAB2. Identified in a pentameric intron-binding (IB) complex composed of AQR, XAB2, ISY1, ZNF830 and PPIE that is incorporated into the spliceosome as a preassembled complex. The IB complex does not contain PRPF19. Excluded from nucleolus. In metaphase II oocytes and in mitotic blastomeres, it is detected in cytoplasm, suggesting that it is not associated with chromosomes during mitosis. Widely expressed at low level. Expressed in oocytes from primordial to antral follicles. Also detected in somatic cells of the ovary, namely, in granulosa cells from the pre-antral follicle stage onward (PubMed:25168238). Expressed in preimplantation embryos. Phosphorylated in response to DNA damage by the cell cycle checkpoint kinases ATR/ATM. Mice die by the end of preimplantation development and exhibit a dramatic reduction in the total cell number, a high mitotic index, and the presence of abnormal mitotic figures. Mice appear unwell with significant loss of body weight and rapidly decline afterwards and die. Mice reveal major alterations of their digestive tract including a distended and filled stomach and an intestine lacking spontaneous peristaltism. The small intestine exhibits a thinner wall, less abundant and stunted villi and highly disorganized crypts. Large portion of the gut are almost devoid of normal epithelial structure (PubMed:23213458). Conditional inactivation of Omcg1 in oocytes leads to sterility and early folliculogenesis arrest (PubMed:25168238).