Fig. 7. The activity of Prf1 is regulated by the concerted action of PKA and MAPK signalling. A model proposing how nutritional or mate sensing is transduced to differential expression of pre- and post-fusion genes. Signalling events during PKA signalling (A) are compared with those during MAPK signalling (B). The prf1-labelled rectangle with a bent arrow symbolizes the prf1 gene. The letters P and M represent PKA and MAPK sites, respectively, whose phosphorylation state is indicated by circled Ps. See text for discussion.