FIG. 1.

PKA and Tor kinase control of the general stress response. Cytoplasmic localization of the general stress response transcription factor Msn2 is independently stimulated by the PKA active subunit Tpk2 and the Tor kinase. Binding of cAMP to the PKA negative regulatory subunit Bcy1 stimulates the release and activation of Tpk2. Phosphorylation of the Msn2 carboxyl terminus by Tpk2 inhibits nuclear import, whereas Tor kinase acts on the Msn2 amino terminus in an unknown way to stimulate efficient nuclear export. Inactivation of either kinase results in the accumulation of Msn2 in the nucleus and the coordinate expression of genes necessary for growth inhibition (YAK1), response to stress (HSP12), and glycogen accumulation (GLC3).