Figure 10. A model for GAME9 control of the steroidal alkaloid pathway and its precursors.
GAME9 activates the synthesis of sterols precursors and SGAs in potato and tomato. GAME9 might activate genes across the pathway indirectly through an intermediate transcription factor (marked ‘TF?') or through co-binding with the SlMYC2 transcription factor. Promoter transactivation assays showed that GAME9/SlMYC2 might be partly regulating SGA biosynthesis by directly activating HMGR1, C5-SD, GAME7 and GAME4 marked in red.