Oocyte and early embryo-specific protein tyrosine kinase that phosphorylates and inhibits cdk1 and acts as a regulator of meiosis in oocytes. Required to ensure the meiotic cell cycle in oocytes by phosphorylating cdk1 at 'Tyr-15', leading to inhibit cdk1 activity and prevent meiosis. ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Interacts with cdca3. Absent in stage VI oocytes and is expressed from meiosis II until gastrulation. Ubiquitinated and degraded at the onset of G2/M phase. Phosphorylated during M and G1 phases. Interacts with cdca3 when phosphorylated at Ser-38. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family. WEE1 subfamily. Was initially assigned as wee1 (PubMed:9486797). However, it corresponds to the meiosis-specific protein WEE2 in mammals.