The function of ENSG00000127564 (PKMYT1, protein kinase, membrane associated tyrosine/threonine 1) is as follows. Acts as a negative regulator of entry into mitosis (G2 to M transition) by phosphorylation of the CDK1 kinase specifically when CDK1 is complexed to cyclins (PubMed:10373560, PubMed:10504341, PubMed:9001210, PubMed:9268380). Mediates phosphorylation of CDK1 predominantly on 'Thr-14'. Also involved in Golgi fragmentation (PubMed:9001210, PubMed:9268380). May be involved in phosphorylation of CDK1 on 'Tyr-15' to a lesser degree, however tyrosine kinase activity is unclear and may be indirect (PubMed:9001210, PubMed:9268380). {ECO:0000269|PubMed:10373560, ECO:0000269|PubMed:10504341, ECO:0000269|PubMed:9001210, ECO:0000269|PubMed:9268380}.