FIG. 1.

Pak1 kinase, but not Cka1 or Tos3, promotes phosphorylation of Snf1 in vitro. (A) Reaction mixtures contained [γ-³²P]ATP and additional purified proteins as indicated. Phosphorylated products were detected by autoradiography. (B) Pak1 kinase-dependent phosphorylation of Snf1 kinase components. A limiting concentration (2.5 ng/ml) of Snf1 kinase purified from pak1Δ mutant cells (lanes 1 to 4) was incubated with either no Pak1 or increasing concentrations of Pak1 kinase purified from snf1Δ10 mutant cells. Snf1 kinase was omitted from the reaction mixture in lane 5.