Serine/threonine protein kinase that contributes to the regulation of cell cycle progression. Involved in meiotic apparatus formation and polar body extrusion. Contributes to Plk1 activation and phosphorylation of histone H3 at 'Ser-10' during meiosis I. Required for accurate progression of early embryonic M phase. Involved in chromosome alignment and cleavage furrow formation during early embryonic cycles. May be involved in mitotic spindle formation and cytokinesis. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Cdc2 activity is required for activation. Localized to cytoplasm in immature oocytes. After 1-methyladenine-induced oocyte maturation during meiosis I, becomes localized initially to the chromosomes, then to both chromosomes and the meiotic spindle, and subsequently relocates from the chromosomes to the midzone at anaphase onset. Expressed in immature oocytes. Expressed at constant levels during meiosis and early embryonic cycles (at protein level). Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.