Like for all aurora-A kinases, the Xenopus pEg2 kinase level peaks in G2/M and is hardly detectable in G1 cells, suggesting that the protein is degraded upon exit from mitosis as reported for the human aurora-A kinase. We identified for the first time a sequence RxxL in the C-terminal end of the kinase catalytic domain. Mutation of this sequence RxxL to RxxI suppresses the ubiquitination of the protein as well as its degradation. The sequence RxxL corresponding to the pEg2 functional destruction box has been conserved throughout evolution in all aurora kinases including aurora-A, -B and -C.
