Essential for the control of the cell cycle at the G2/M (mitosis) transition. Interacts with the CDK1 protein kinase to form a serine/threonine kinase holoenzyme complex also known as maturation promoting factor (MPF) (By similarity). The cyclin subunit imparts substrate specificity to the complex (By similarity). Interacts with E3 ubiquitin-protein ligase etc-1 (PubMed:23578927). Expressed in mature oocytes followed by a severe reduction in protein levels as meiotic division progresses (PubMed:23578927). Ubiquitinated by etc-1 likely during meiosis, resulting in its degradation. Belongs to the cyclin family. Cyclin AB subfamily.