Domain structure of the α, β and γ subunits of AMPK and their isoforms. KEY: α-subunits: AID, auto-inhibitory domain, α-CTD, C-terminal domain; β-subunits: CBM, carbohydrate-binding module; β-CTD, C-terminal domain; γ subunits: CBS1, CBS2, CBS3, CBS4, cystathione β-synthase repeats; γ2-NTD, N-terminal extension of “long” version of γ2 subunit; γ3-NTD, N-terminal extension of “long” version of γ3 subunit.