Relationship tree based on the catalytic domain of
the Arabidopsis Ser/Thr protein kinases. The sequence-based
relationship between AtSK, AtMAP3K, and
AtMAP4K, compared with the other groups of S/T kinases, is
presented in the tree. In bold are indicated the major groups of S/T
kinases, i.e. the receptor-like kinases (RLK) and the RAF kinases
(standard characters), as well as the non-receptor S/T kinases, such as
CMGC, AGC, CaMK, and STE (comic characters), as defined by Hunter and
Plowman (1997). The 10 AtSK genes, the two
AtMAP3Kεs, and the two AtMAP4Kαs are typed in
bold small characters. The distance tree was constructed using the
neighbor-joining method (Saitou and Nei, 1987) via the ClustalX
program. We rooted the tree using the sequences of Arabidopsis RLK. The
tree, including 52 RAF and 316 non-receptor S/T kinases, has been
simplified. The bootstrap values of 100 replicates are only indicated
for the AtSK, the AtMAP3Kε, and the
AtMAP4Kα proteins.