Kinase Subfamily MEK5

Kinase Classification: Group STE: Family STE7: Subfamily MEK5

MEK5 phosphorylates ERK5 as part of the ERK5-variant MAPK pathway

Evolution

MEK5 is found as a single copy, only in animals. It is secondarily lost from most insects and nematodes, along with its pathway members, MEK5 and MEKK2. Vertebrates have a single copy, known as MEK5, MAPKK5, or MAP2K5. Possible homologs are found in fungi, including S. cerevisiae MKK1 and MKK2, and their upstream and downstream kinases are also possible members of the ERK5 pathway.

Domain Structure

MEK5 kinases have an N-terminal PB1 domain that mediates dimerization with the upstream MEKK2 and PKCi kinases, and a C-terminal kinase domain.

Control of activity

As part of the ERK5 cascade, MEK5 is phosphorylated and activated by kinases MEKK2 subfamily kinases. It can also be activated by atypical Protein Kinase C (Subfamily PKCi), the only animal kinases other than MEK5 and MEKK2 to have a PB1 dimerization domain.

Functions

MEK5 is tightly linked to the activation of ERK5. See the ERK5 article for more information on functions of this cascade.