Fig. 4

Proposed Model. bE and bW proteins derived from opposite mating type form functional transcriptional complex to activate or repress Class 1 (direct) target genes. Class 2, indirect targets, are in turn activated or repressed by products encoded by Class 1 targets. Starch/sucrose metabolism genes as well as HOG1 may be indirectly repressed by the bE/bW transcriptional complex, during mating. b-repressed glucose metabolism gene may promote production of glucose, which may repress mating and/or filamentous growth. Meanwhile, glucose production may lead to elevated intracellular oxidative level, and thus induce Hog1 MAPK pathway, which also negatively regulates mating and/or filamentous growth. Overall, b-locus may act in shutting down mating/filamentous growth inhibitors, including high level of glucose and Hog1 MAPK signaling