Figure 1.

Activation of AMPK-related kinases by LKB1. (A) Dendrogram and T-loop sequences of AMPK subfamily of protein kinases (Manning et al, 2002). The identical residues are shaded black and the conserved residues in grey. The T-loop Thr and Ser are indicated with an asterisk. (B) The indicated AMPK-related kinases were incubated with wild-type LKB1:STRAD:MO25 (open squares) or catalytically inactive LKB1[D194A]:STRAD:MO25 (open circles) complexes in the presence of Mg²⁺ and ATP. At the indicated times, the activity of the AMPK-related kinases was assayed with the AMARA peptide, and the results are expressed as specific activity. Results shown are means±s.d. of assays carried out in triplicate and representative of two independent experiments. The error bars are only shown when larger than the size of the open squares. The suggested consensus sequence for optimal LKB1 phosphorylation is indicated. Ø represents a large hydrophobic residue; X, any amino acid; s, n, g and a preferences for Ser, Asn, Gly and Ala, respectively.