for direct phosphorylation of its other CDKs and that there is no Cak1p-related kinase. Both yeasts have a TTK member, which is known to play roles both in spindle pole duplication and in the spindle checkpoint response that monitors attachment of chro- mosomes to the mitotic spindle. The spindle pole duplication role is conserved in mammals although apparently not 
in fission yeast, and it is this function that makes MPS1 essential in S. cerevisiae. Since E. cuniculi lacks a Bub1p homologue, another key kinase in the checkpoint pathway, it is likely that the microsporidian TTK is involved primarily in spindle pole duplication. Yeast Yak1p is a member of the conserved DYRK sub-family that is represented in fission yeast by the as yet uncharacterized Ppk15. Budding yeast Yap1p is involved in glucose signalling and is associated with growth inhibition, functioning in an antagonistic manner either downstream of or in parallel with the PKA pathway. The presence of a DYRK member in E. cuniculi is therefore consistent with the presence of a PKA orthologue and suggests that the functional relationship between PKA and DYRK has been conserved in the microsporidian. Page 12 of 21 BMC Genomics 2007, 8:309 http://www.biomedcentral.com/1471-2164/8/309 Casein kinase II is a multifunctional enzyme with roles in processes as diverse as cell cycle progression, cell polarity and ion homeostasis. The presence of an E. cuniculi orthologue underlines the fundamental importance of this group of kinases and is consistent with the identification of a Casein Kinase II regulatory subunit. Comparing the two model yeasts, most members of the CMGC family show orthologous relationships and there are few apparently lineage-specific ‘semiorphans’. Members of this family that are found in the yeasts but not the microsporidian include the MAP kinases, members of the RCK sub-group and GSK3, which in budding yeast is involved in meiotic induction and in heat stress tolerance. STE family All the STE kinases of S. cerevisiae and S. pombe were found to share homology relationships, but no kinases of the STE family were found in E. cuniculi. The presence of putative MAPKKK-MAPKK-MAPK modules in the kinomes of the three Trypanosomatid species suggests that these are likely to have been lost in a number of reduced kinomes such as those of P. falciparum, other Apicomplexa and E. cuniculi. However, a number of key STE family members function in pathways distinct from MAP kinase pathways in the yeasts, for example Cdc15p/Cdc7, which forms part of the MEN/SIN late mitotic network. Some STE20 family members, such as budding yeast Ste20p itself, function upstream of MAP kinase pathways. However, not all of their roles are mediated in this way and so it seems that these other roles are not required in E. cuniculi. Several of the STE kinases are Rho GTPaseactivated kinases, characterised by a PB domain that binds the p21 GTPase and purchase 2883-98-9 sometimes a PH domain upstream of this. Page 13 of 21 BMC Genomics 2007, 8:309 http://www.biomedcentral.com/1471-2164/8/309 Other protein kinases This group is constituted by ePKs that cannot be classified confidently into any of the main ePK families. The multilevel HMM library has been used to classify some of the ‘Other’ kinases of S. cerevisiae into the main ePK families by comparison with syntenic homologous genes of the related fungus Ashbya gossypii. However, some of the ‘Other’ kinases PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19793655 of S. cerevisiae are likely to constitute yeastspecific families
