Inhibits DNA replication by binding to the DNA replication licensing factor cdt-1 (PubMed:15811859). Its interaction with cdt-1 prevents the cdt-1 loading of the mini-chromosome maintenance (MCM) complex onto DNA and therefore DNA replication licencing (PubMed:15811859). Homodimer (PubMed:15811859). Interacts with cdt-1; the interaction most likely inhibits the ability of cdt-1 to load the mini-chromosome maintenance (MCM) complex onto DNA and therefore reduces DNA replication licensing activity (PubMed:15811859). Interacts with nob-1 and ceh-32 (PubMed:15811859). Mainly cytoplasmic, but can be re-localized to the nucleus. RNAi-mediated knockdown results in sterility in 20% of animals (PubMed:15811859). Sterile animals have severe oogenesis defects and partially differentiated germ cells accumulate in the proximal arm of the gonad (PubMed:15811859). Furthermore, germ nuclei in the distal region of the gonad are enlarged, and their nucleoli are misshapen (PubMed:15811859). Sterile animals also have mitotic defects whereby pairs of chromosome bridge, which is indicative of a defect in coordination between endoreduplication and the nuclear division cycle (PubMed:15811859). Belongs to the geminin family.