Mik1
Mik1 is a protein kinase in the fission yeast Schizosaccharomyces pombe encoded by the mik1+ gene. It is a member of the Wee1 family of inhibitory kinases that regulate Cdc2 (Cdk1) activity. Mik1 functions as a negative regulator of mitotic entry by phosphorylating the tyrosine 15 residue of Cdc2, thereby inhibiting its kinase activity and delaying entry into mitosis. It operates in parallel with Wee1, and both kinases contribute to the G2/M checkpoint and to cell cycle timing. In the absence of Mik1, cells show a mild delay or normal progression depending on conditions, but loss of both Mik1 and Wee1 leads to a strong disruption of G2 control and can cause premature or defective mitosis.
Regulation occurs in response to DNA replication status and DNA damage, with the checkpoint signaling maintaining
Structurally, Mik1 contains a catalytic kinase domain with similarity to Wee1 family kinases and regulatory regions
As a model organism gene, Mik1 helps illustrate redundancy and robustness in eukaryotic cell cycle control;