We have analysed phosphorylation of the synthetic peptide AMARAASAAALARRR, and 23 variants, by mammalian, higher plant and yeast members of the SNF1 protein kinase subfamily (AMP-activated protein kinase (AMPK), HMG-CoA reductase kinase (HRK-A), and SNF1 itself), and by mammalian calmodulin-dependent protein kinase I (CaMKI). These four kinases recognize motifs which are very similar, although distinguishable. Our studies define the following recognition motifs: AMPK: Φ(X,β)XXS/TXXXΦ; HRK-A: Φ(X,β)XXSXXXΦ; Snf1: ΦXRXXSXXXΦ; CaMKI: ΦXRXXS/TXXXΦ; where Φ is a hydrophobic residue (M, V, L, I or F) and β is a basic residue (R, K or H).
